799 lines
34 KiB
Plaintext
799 lines
34 KiB
Plaintext
TURBO C++: ANSWERS TO COMMON QUESTIONS
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G e t t i n g S t a r t e d
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----------------------------------------------------------------------
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Q. How do I install Turbo C++?
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A. Run the INSTALL program from the INSTALL/HELP disk. To start
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the installation, change your current drive to the one that
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has the install program on it and type INSTALL. You will be
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given instructions in a box at the bottom of the screen for
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each prompt. For example, if you will be installing from
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drive A:, type:
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A:
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INSTALL
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At this point, the INSTALL program will appear with menus
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selections and descriptions to guide you through the installation
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process.
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Q. How do I run Turbo C++?
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A. After you have installed Turbo C++, type "TC" from the DOS
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prompt and you're ready to go.
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Q. What is the difference between TC.EXE and TCC.EXE?
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A. The Turbo C++ package comes with two compilers, an Integrated
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Environment named TC.EXE and a command-line compiler named
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TCC.EXE. The Integrated Environment combines the command-line
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compiler with an integrated editor, linker, debugger, and other
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useful features (such as pop-up and pull-down menus, full keyboard
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and mouse support, and so on). The command-line version runs from
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the DOS command line. Please refer to the Turbo C++ User's Guide
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for details on using both systems.
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Q. What is a configuration file?
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A. A configuration file tells Turbo C++ what options to default to
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and where to look for its library and header files. TC.EXE
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looks for a configuration file named TCCONFIG.TC, and TCC.EXE
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looks for a file named TURBOC.CFG.
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Q. How do I create a configuration file?
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A. When you run the INSTALL program it creates a configuration
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file named TURBOC.CFG for TCC.EXE. This file is just an
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ASCII file which you can change with any text editor. It
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contains the path information for the library and header
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files for TCC.EXE to use. The INSTALL program does not
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create a TCCONFIG.TC file for TC.EXE because it installs
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the directory information directly into TC.EXE. You can
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create a configuration file for TC.EXE by running Turbo C++,
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setting your options however you want to set them, and
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typing Alt-O/S.
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C o m m o n C + + Q u e s t i o n s
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----------------------------------------------------------
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Q: When linking C or Assembly language modules with C++ modules I get
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undefined symbol errors at link time. It appears that none of the C
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or Assembly public symbols can be found.
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A: C++ is a strongly typed language. In order to support the language
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to its fullest, Turbo C++ must attach information to the symbols
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generated for function names and variables. When this is done, the
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symbol will no longer match the standard C style function name. In
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order to link correctly, the compiler must be notified that the symbol
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is declared in an external module without type information tacked on
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to the symbol. This is done by prototyping the function as type
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extern "C". Here is a quick example:
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extern "C" int normal_c_func( float, int, char ); // name not altered
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void cplusplus_function( int ); // name altered
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See related comments under Linker Errors and in Paradox Engine
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question in this section.
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Q. What potential problems can arise from typecasting a base
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class pointer into a derived class pointer so that the derived
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class's member functions can be called?
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A. Syntactically this is allowable. There is always a possibility of
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a base pointer actually pointing to a base class. If this is
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typecast to a derived type, the method being called may not exist
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in the base class. Therefore, you would be grabbing the address of
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a function that does not exist.
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Q: What's the difference between the keywords STRUCT and CLASS?
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A: The members of a STRUCT are PUBLIC by default, while in CLASS,
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they default to PRIVATE. They are otherwise functionally equivalent.
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Q: I have declared a derived class from a base class, but I can't access any
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of the base class members with the derived class function.
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A: Derived classes DO NOT get access to private members of a base class.
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In order to access members of a base class, the base class members must
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be declared as either public or protected. If they are public, then
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any portion of the program can access them. If they are protected, they
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are accessible by the class members, friends, and any derived classes.
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Q: How can I use the Paradox Engine with C++?,
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A: Because the Paradox Engine functions are all compiled as C functions
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you will have to assure that the names of the functions do not get
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"mangled" by the C++ compiler. To do this you need to prototype the
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Engine functions as extern "C". In the pxengine.h header file insert
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the following code at the lines indicated.
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/* inserted at line # 268 */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* inserted at line # 732, just before the final #endif */
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#ifdef __cplusplus
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}
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#endif
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Q: I have a class that is derived from three base classes. Can I insure that
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one base class constructor will be called before all other constructors?
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A: If you declare the base class as a virtual base class, its constructor
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will be called before any non-virtual base class constructors. Otherwise
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the constructors are called in left-to-right order on the declaration
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line for the class.
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Q: Are the standard library I/O functions still available for use with
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the C++ iostreams library?
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A: Yes, using
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#include <stdio.h>
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functions such as printf() and scanf() will continue to be
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available.
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Q: When debugging my program in Turbo Debugger, I notice that none of my
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inline functions are expanded inline. Instead, they are all done as
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function calls.
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A: Whenever you compile your program with debugging information included,
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no functions are expanded inline. To verify that your inline functions
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are indeed expanding inline, compile a module with the -S flag of the
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command-line compiler, then examine the .asm file that is generated.
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Q. In C++, given two variables of the same name, one local and one global,
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how do I access the global instance within the local scope?
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A. Use the scope (::) operator.
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int x = 10;
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for(int x=0; x < ::x; x++)
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{
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cout << "Loop # " << x << "\n"; // This will loop 10 times
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}
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Q. Will the following two functions be overloaded by the compiler, or
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will the compiler flag it as an error? Why?
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void test( int x, double y); & int test( int a, double b);
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A. The compiler will flag this as a redeclaration error because
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neither return types nor argument names are considered when determining
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unique signatures for overloading functions. Only number and type
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of arguments are considered.
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Q. If I pass a character to a function which only accepts an int,
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what will the compiler do? Will it flag it as an error?
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A. No. The compiler will promote the char to an int and use the integer
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representation in the function instead of the character itself.
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Q. I was trying to allocate an array of function pointers using the new
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operator but I keep getting declaration syntax errors using the following
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syntax: new int(*[10])(); What's wrong?
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A. The new operator is a unary operator and binds first to the int keyword
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producing the following: (new int) (*[10])();
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You need to put parentheses around the expression to produce the
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expected results: new (int (*[10]());
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Q. What are inline functions? What are their advantages? How are they
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declared?
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A. An inline function is a function which gets textually inserted by
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the compiler, much like macros. The advantage is that execution time
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is shortened because linker overhead is minimized. They are declared
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by using the inline keyword when the function is declared:
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inline void func(void) { cout << "printing inline function \n"; }
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or by including the function declaration and code body within a class:
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class test
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{
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public:
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void func(void) { cout << "inline function within a class.\n"}
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};
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Q. If I don't specify either public or private sections in a class,
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what is the default?
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A. A class will default all members to private if neither public nor
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private sections are declared.
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Q. What does the _seg modifier do?
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A. Using _seg cause a pointer to become a storage place for a
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segment value, rather than an offset ( or a segment/offset ).
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For instance, if "int _seg *x" contains the value 0x40,
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then when you use "*x", the value pointed to will be at
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segment 0x40, offset 0. If you add a value to the pointer,
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the value is multiplied by the size of the pointer type. That
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new value is used as an offset, and is combined with the segment
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value contained in the pointer. For instance,
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int _seg *x;
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int value;
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x = (int _seg *)0x40;
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value = *(x + 20);
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value is assigned the value of the integer at 0x40:0x28
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(Remember, 20 * sizeof(int) = 40 = 0x28).
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Q. Can I statically allocate more than 64K of data in a single module?
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A. Yes. Far data items are now supported:
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...
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char far array1[60000L];
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char far array2[60000L];
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...
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For arrays larger than 64k use:
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char huge array3[100000L];
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Q. Why do I get a "Type name expected" error on my definition of a
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friend class in my new class?
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A You need to let the compiler know that the label you use for your
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friend class is another class. If you do not want to define your
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entire class, you can simply have "class xxx", where xxx is your
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label.
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Q: How can I output hex values in upper case using the iostream libraries?
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A: You need to set the state of the stream using setf(). For example,
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#include <iostream.h>
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int main(void)
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{
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cout << hex;
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cout << "\nNot upper-case : " << 255;
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cout.setf(ios::upper-case);
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cout << "\nUppercase : " << 255;
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return 0;
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}
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Q. What is the "this" pointer?
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A. "this" is a local variable in the body of a non-static member function.
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It is a pointer to the object for which the function was invoked. It
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cannot be used outside of a class member function body.
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Q. Why does a binary member function only accept a single argument?
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A. The first argument is defined implicitly.
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Q. What is a friend member function?
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A. Declaring a friend gives non-members of a class access to the
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non-public members of a class.
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Q: Looking through the class libraries there are definitions in classes
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which look like:
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class test {
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int funct( void ) const;
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};
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What is the const keyword doing here?
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A: There is a pointer to the object for which a function is called
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known as the 'this' pointer. By default the type of 'this'
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is X *const ( a constant pointer). The const keyword changes the
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type to const X *const ( a constant pointer to constant data ).
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Q: I want to use _new_handler and set_new_handler, but I do not
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see them referenced anywhere.
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A: Turbo C++ supports _new_handler and set_new_handler even though they
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are not explicitly defined in the AT&T 2.0 language specification.
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The type of _new_handler is as follows.
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typedef void (*vfp)(void);
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vfp _new_handler;
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vfp set_new_handler( vfp );
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Q: I would like to use C++ fstreams on a file opened in binary mode,
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how is this done?
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A: Use ios::binary as the open mode for the file:
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#include <fstream.h>
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ifstream binfile;
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binfile.open("myfile.bin", ios::binary);
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Q: How can I get at the DOS file handle associated with my iostream?
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A: Using a combination of member functions fd() and rdbuf() you can
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get at the file handle.
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#include <fstream.h>
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#define fstrno(s) (((s).rdbuf())->fd())
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ifstream test("test.txt");
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cout << "handle is " << fstrno(test) << '\n';
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I n t e g r a t e d E n v i r o n m e n t
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----------------------------------------------------------------------
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Q: Why doesn't my mouse work well with Turbo C++?
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A: More often then not you will need to get a newer version of
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the driver for your particular mouse. Check the list on page 3 of
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the User's Guide for most common mouse drivers. In addition
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to that list:
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Logitech driver 4.0+ is needed to use the mouse in 43/50 line mode.
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Genius driver version 9.0+ is needed for compatibility.
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Q. Why is Turbo C++ not able to find any of my #include files?
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A. The compiler searches for include files in the Turbo C++ Include
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Directories path. You can specify this path through the
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Options|Directories menu. The INSTALL program initially sets this
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path to the directory where it copied all the Turbo C++ *.h files.
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Q. How can I issue a DOS command in the Programmer's Platform?
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A. Go to Options|Transfer and enter a new item by moving to the first
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empty line and selecting Edit. Enter the name you'd like to use
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(you could call it "DOS Shell") in Program Title. Move to Program
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Path and enter the name of your command processor (like
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"C:\COMMAND.COM"), then move to Command Line and enter "/c
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$PROMPT". Select New to store the new transfer item.
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You'll then see the new entry for the System menu (use Alt-Space),
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and if you select it you can enter the DOS command on the prompt
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line, use the history list, etc.
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Q. I'm seeing a box that says "Internal Error - Report to Borland" -
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what does it mean?
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A. The most likely cause for this error is that you attempted either
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to load or unload a TSR like the PRINT command or SideKick while
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in a DOS shell from the Programmer's Platform. Resident programs
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should not be loaded or unloaded while in an application's DOS
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shell.
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Q. Why do I get the message:
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Linker Error: Unable to open input file 'C0x.OBJ'
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A. The linker searches for Turbo C++ start-up and library files in the
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Turbo C++ Library Directories path. You can specify this path through
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the Options|Directories menu. The INSTALL program initially sets this
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path to the directory where it copied the start-up and library files.
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Q. How do I get Turbo C++ to link in my own libraries or use multiple
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source files?
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A. Turbo C++'s Project facility is designed to allow you to work with
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multiple files.
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Q. Why does the linker tell me that all the graphics library routines
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are undefined?
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A. The Options|Linker|Graphics Library item must be set ON, if
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you are using any Turbo C++ graphics functions and have not
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specified GRAPHICS.LIB in a project file.
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Q. Why does Turbo C++ report "Unable to open include file 'stdarg.h'"
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when I try to #include <stdio.h>?
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A. The most probable reason is that you have exceeded the number
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of files that DOS can have open simultaneously. Add the line
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FILES=20
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to your DOS CONFIG.SYS file. This allows DOS to open up to 20
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files at the same time. CONFIG.SYS will only be effective after
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you have rebooted your computer. See the IBM DOS Reference
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Manual for details on the CONFIG.SYS file.
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Q. How do I change the colors of the editor and menus in TC?
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A. The utility TCINST.EXE allows you to customize your colors.
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Q. How do I get a listing of my source code to my printer?
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A. From within the Turbo C++ editor press Ctrl-K-P. This will
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print a marked block to the printer. If no block is marked,
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this key sequence will print the entire file in your editor.
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Q. When I Make, Run, or Trace a program, Turbo C++ sometimes goes
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through the compile and link process even when the object files
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are up-to-date.
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A. Turbo C++'s MAKE logic works solely on a file's date and time
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stamp. If one of your source files is marked with a date
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that's sometime in the future, the object files that are
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created from it will always be older than the source file,
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and Turbo C++ will always try to rebuild the file. You can fix
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this by using TOUCH.COM to set the file to the current date
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and time. You should also make sure that your system's date
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and time are always properly set. TOUCH.COM is documented in
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the file UTIL.DOC.
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Q. How come my old Turbo C++ project files don't work anymore?
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A. Project files now contain much more information about a project now,
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and hence are no longer stored in ASCII format. To create a project
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file, select PROJECT from the main menu, and follow the menus. To
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convert your old project files to the new format, use the supplied
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utility file PRJCNVT.EXE (documented in UTIL.DOC).
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Q. How can I convert my Turbo C 2.0 project files to the new
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format?
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A. There is a conversion utility in your Turbo C++ BIN directory
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called PRJCNVT.EXE. This program will perform the conversion.
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Q. How come my project file is automatically loaded when I start TC. I
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want to work on a different program.
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A. If there is only one project file in the current directory, Turbo C++
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will load and use that one file. If there are no project files, or
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if there are multiple project files, Turbo C++ does not automatically
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load one.
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Q. My right mouse button appears to do nothing. Can I change this so it
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will set breakpoints?
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A. Yes, under the menu for Options|Environment|Mouse there is a
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dialog box for the right mouse button. You can change it to set
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breakpoints, or to do many other things.
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Q. How do I get Turbo C++ to use extended or expanded memory?
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A. Use the /X switch for extended and the /E switch for expanded when
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you invoke Turbo C++.
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Q. How can I find out where my "null pointer assignment" is occurring?
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A. Set a watch on the following expressions:
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*(char *)0,4m
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(char *)4
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Step through the program. When the values change, the just-executed line
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is the one that is causing the problem.
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Q. When I compile my program, I get the following error:
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Error: C:\TC\INCLUDE\STDIO.H: Overlays only supported in
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medium, large, and huge memory models
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What is happening?
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A. The Overlay Support option has been selected and does not work
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in the tiny or small memory models.
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You may turn this option off with:
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Options|Compiler|Code Generation|Overlay Support
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Q. When I try to load a new file after editing a file, the first
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file remains on the screen. How do I close the first file?
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A. Use Alt-F3 to close the current file. Also, use F6 to move
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from one file to the next, if there is more than one file
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open at a time.
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Q. I'm doing a search and replace operation, and the editor prompts me for
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each replacement. I've selected "Change All", but it still does it.
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A. To disable the prompting, you must unselect the "Prompt on replace"
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option on the left side of the dialog box.
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Q. When I try to use the any of the pseudo registers, like _AX, I
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get the error message "Undefined symbol '_AX' in function..."
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when I compile. Why?
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A. You are only allowed to use the pseudo registers in the Turbo
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C++ and ANSI modes of the compiler. You can change this setting
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in the Options|Compiler|Source menu.
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Q. Since I don't have a mouse, can I still copy blocks of code
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from one file to another?
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A. Yes. You can mark the beginning and end of a block by moving
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to the appropriate area and pressing Ctrl-K-B (mark beginning) and
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Ctrl-K-K (mark end). You can then use the copy and paste commands
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in the Edit menu.
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Q: The changes I am making using the TCINST utility are not taking effect.
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A: Any options or colors saved directly to TC.EXE using TCINST.EXE may be
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overridden by the contents of a configuration file or a project file.
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When Turbo C++ begins running, it first determines if there is only
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one project file in the current directory. If there is, this project
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file will automatically be loaded. Turbo C++ will then look for a
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file with a .tc extension in either the current directory or the
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directory in which the Turbo C++ executable resides, loading it if
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it can be found.
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Q: How do I stop all of the files I have ever edited from constantly
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being open when I bring up Turbo C++?
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A: By default, Turbo C++ saves what is called the desktop configuration.
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This configuration is saved in a file with a .dsk extension. By deleting
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any files of this type then entering Options/Environment/Preferences
|
||
and removing the check from 'auto save desktop', you will begin with a
|
||
clean desktop each time TC is invoked.
|
||
|
||
|
||
C o m m a n d - L i n e C o m p i l e r
|
||
----------------------------------------------------------------------
|
||
Q. Why is Turbo C++ not able to find any of my #include files?
|
||
A. The compiler searches for include files in the Turbo C++ Include
|
||
Directories path. You specify this path with the -I switch. The INSTALL
|
||
program initially writes a configuration file (TURBOC.CFG) that
|
||
sets this path to the directory where it copied all the Turbo C++
|
||
*.h files.
|
||
|
||
Q. Why do I get the message:
|
||
Linker Error: Unable to open input file 'C0x.OBJ'
|
||
A. The linker searches for Turbo C++ start-up and library files in the
|
||
Turbo C++ Library Directories path. You can specify this path with
|
||
the -L switch. If you allow TCC to invoke the linker, it will search
|
||
the directories in the configuration file (TURBOC.CFG) written by the
|
||
INSTALL program. If you run TLINK, the configuration file is not read.
|
||
|
||
Q. Why does the linker tell me that all the graphics library
|
||
routines are undefined?
|
||
A. TCC will not search the graphics library unless you tell it to.
|
||
You should specify the graphics library on the command line. For
|
||
example, to compile BGIDEMO, type
|
||
|
||
TCC BGIDEMO.C GRAPHICS.LIB<Enter>
|
||
|
||
|
||
G e n e r a l I / O
|
||
----------------------------------------------------------------------
|
||
Q. The '\n' in cprintf() does not return the cursor to the
|
||
beginning of the line. It only moves the cursor down one line.
|
||
A. cprintf() interprets '\n' as a Line Feed. To force the cursor to
|
||
the beginning of the line, manually insert a Carriage Return:
|
||
|
||
cprintf("\n\r");
|
||
|
||
Q. How do I print to the printer from a Turbo C++ program?
|
||
A. Turbo C++ uses a FILE pointer (stdprn) defined in the STDIO.H
|
||
file. You do not need to open stdprn before using it:
|
||
|
||
#include <stdio.h>
|
||
int main(void)
|
||
{
|
||
fprintf(stdprn, "Hello, world\n");
|
||
}
|
||
|
||
Note that if your printer is line-buffered, the output is
|
||
flushed only after a '\n' is sent.
|
||
|
||
Q. I am reading and writing binary files. My program is translating
|
||
the Carriage Return (0x0D) and Line Feed (0x0A) characters. How do
|
||
I prevent this from happening?
|
||
A. Files opened in text mode will translate these characters for
|
||
DOS. To read a file in binary mode, open it in binary mode.
|
||
For example,
|
||
|
||
#include <stdio.h>
|
||
int main(void)
|
||
{
|
||
FILE *binary_fp;
|
||
char buffer[100];
|
||
|
||
binary_fp = fopen("MYFILE.BIN", "rb");
|
||
|
||
fread(buffer, sizeof(char), 100, binary_fp);
|
||
|
||
:
|
||
}
|
||
|
||
The default file mode is text.
|
||
|
||
Q. Why don't printf() and puts() print text in color?
|
||
A. Use the console I/O functions cprintf() and cputs() for color output.
|
||
|
||
#include <conio.h>
|
||
int main(void)
|
||
{
|
||
textcolor(BLUE);
|
||
cprintf("I'm blue.");
|
||
}
|
||
|
||
Q. How do I print a long integer?
|
||
A. Use the "%ld" format:
|
||
|
||
long int l = 70000L;
|
||
printf("%ld", l);
|
||
|
||
Q. How do I print a long double?
|
||
A. Use the "%Lf" format.
|
||
|
||
long double ldbl = 1E500;
|
||
printf("%Lf", ldbl);
|
||
|
||
|
||
E x a m p l e P r o g r a m s
|
||
----------------------------------------------------------------------
|
||
Q. How do I compile the BGIDEMO program?
|
||
A. 1. Make sure that the following Turbo C++ files are in your
|
||
current directory:
|
||
|
||
BGIDEMO.C
|
||
*.BGI
|
||
*.CHR
|
||
|
||
2. Run Turbo C++.
|
||
|
||
3. Load BGIDEMO.C into the Editor by pressing F3, then typing
|
||
BGIDEMO<Enter>
|
||
|
||
3. Go to the Run menu and choose the Run item.
|
||
|
||
Q. How do I create a COM file?
|
||
A. DOS versions 3.2 and earlier include an EXE2BIN utility that
|
||
converts EXE files to COM files. Users who do not have EXE2BIN can
|
||
use TLINK, the Turbo C++ command-line linker, to create a COM file
|
||
instead of an EXE file. Use the /t option. For example:
|
||
|
||
tcc -mt -lt tiny
|
||
|
||
will create TINY.COM instead of TINY.EXE.
|
||
|
||
There are certain limitations in converting an EXE file to a COM
|
||
file. These limitations are documented in the IBM Disk Operating
|
||
System manual under EXE2BIN.
|
||
|
||
Turbo C++'s TINY model is compatible with the COM format, but programs
|
||
that use Turbo C++'s floating-point routines cannot be converted to a
|
||
COM file.
|
||
|
||
|
||
G r a p h i c s
|
||
----------------------------------------------------------------------
|
||
Q. Why do I get the error message:
|
||
|
||
BGI Error: graphics not initialized (use 'initgraph')
|
||
|
||
when I use a graphics function? My program has already
|
||
called initgraph().
|
||
A. For some reason initgraph() failed. To find out why, check
|
||
the return value of graphresult(). For example:
|
||
|
||
#include <graphics.h>
|
||
int main(void)
|
||
{
|
||
int gerr; /* graphics error */
|
||
int gdriver = DETECT, gmode;
|
||
|
||
/* Initialize graphics using auto-detection and look
|
||
for the .BGI and .CHR files in the C:\TURBOC directory.
|
||
*/
|
||
initgraph(&gdriver, &gmode, "C:\\TURBOC");
|
||
|
||
if ((gerr = graphresult()) != grOk)
|
||
{
|
||
printf("Error : %s\n", grapherrormsg(gerr));
|
||
exit(1);
|
||
}
|
||
:
|
||
}
|
||
|
||
|
||
M a t h / F l o a t i n g P o i n t
|
||
----------------------------------------------------------------------
|
||
Q. Why do I get incorrect results from all the math library
|
||
functions like cos(), tan() and atof()?
|
||
A. You must #include <math.h> before you call any of the standard
|
||
Turbo C++ math functions. In general, Turbo C++ assumes that a function
|
||
that is not declared returns an int. In the case of math functions,
|
||
they usually return a double. For example
|
||
|
||
/* WRONG */ /* RIGHT */
|
||
#include <math.h>
|
||
int main(void) int main(void)
|
||
{ {
|
||
printf("%f", cos(0)); printf("%f", cos(0));
|
||
} }
|
||
|
||
Q. How do I "trap" a floating-point error?
|
||
A. See the signal() and matherr() functions in the Turbo C++ Library
|
||
Reference. The signal() function may be used to trap errors in the
|
||
80x87 or the 80x87 emulator. The matherr() function traps errors
|
||
in the Math Library functions.
|
||
|
||
|
||
L i n k e r E r r o r s
|
||
----------------------------------------------------------------------
|
||
Q. I am linking C functions with C++ functions. The linker reports that
|
||
all of my C functions are undefined. Why?
|
||
A. Linking C++ modules with C modules requires the use of a linkage
|
||
specification. Prototypes for C functions within C++ modules must
|
||
be in one of the following forms:
|
||
extern "C" declaration
|
||
extern "C" { declarations }
|
||
For example, if a C module contains functions
|
||
"char *SCopy(char*, char*);" and "void ClearScreen(void)", they
|
||
must be declared in a C++ module in one of the following ways:
|
||
extern "C" char *SCopy(char*, char*);
|
||
extern "C" void ClearScreen(void);
|
||
or
|
||
extern "C" {
|
||
char *SCopy(char*, char*)
|
||
void ClearScreen(void);
|
||
}
|
||
For further examples, see the standard header files. For additional
|
||
comment, see Common C++ Questions.
|
||
|
||
Q. Why do I get the message:
|
||
Linker Error: Unable to open input file 'C0x.OBJ'
|
||
A. See "Integrated Environment" section above.
|
||
|
||
Q. Why do I get the message:
|
||
Linker Error: Undefined symbol '_main' in module C0
|
||
A. Every C program must contain a function called main(). This
|
||
is the first function executed in your program. The function
|
||
name must be all in lower case. If your program does not
|
||
have one, create one. If you are using multiple source files,
|
||
the file that contains the function main() must be one of
|
||
the files listed in the Project.
|
||
|
||
Note that an underscore character '_' is prepended to all
|
||
external Turbo C++ symbols.
|
||
|
||
Q. Why does the linker tell me that all the graphics library
|
||
routines are undefined?
|
||
A. See the "Integrated Environment" and "Command-line Compiler"
|
||
sections above.
|
||
|
||
Q. What is a 'Fixup overflow'?
|
||
A. See the listing of TLINK error messages in the Turbo C++
|
||
User's Guide.
|
||
|
||
Q. I am linking my own assembly language functions with Turbo C++.
|
||
The linker reports that all of my functions are undefined.
|
||
A. Make sure that you have put an underbar character '_' in front of all
|
||
assembly language function names to be called by Turbo C++. Your assembly
|
||
language program should be assembled with Case Sensitivity.
|
||
|
||
Q: I am getting an error out of the linker "segment group exceeds 64K :
|
||
_text".
|
||
A: If you are using the BGIOBJ utility, the default segment into which
|
||
the objects will be place is _text. You should try using BGIOBJ with
|
||
a /f switch to place the resultant objects into a separate segment.
|
||
You will then need to use the functions registerfarbgidriver and
|
||
registerfarbgifont to register the objects for the graphics system.
|
||
See UTIL.DOC for instructions on using these functions.
|
||
|
||
Q: I am attempting to link TC 2.0 objects into my Turbo C++ programs, but
|
||
continually get unresolved external symbols at link time.
|
||
A: Many of the "helper" functions in have changed name from TC 2.0 to TC++.
|
||
If you are getting undefined symbols like _LXLSH and _FMUL, this is
|
||
the problem you are running into. Your best solution would be to get
|
||
the source code to the old object modules and recompile with TC++.
|
||
The only other possibility would be to extract the helper function
|
||
objects from the Turbo C 2.0 libraries and link them into the
|
||
TC++ program.
|
||
|
||
O t h e r Q u e s t i o n s
|
||
----------------------------------------------------------------------
|
||
Q. How do I change the stack size?
|
||
A. The size of the stack of a Turbo C++ program is determined at
|
||
run time by the global variable _stklen. To change the size
|
||
to, for example, 10,000 bytes, include the following line in
|
||
your program:
|
||
|
||
extern unsigned _stklen = 10000;
|
||
|
||
This statement must not be inside any function definition.
|
||
The default stack size is 4,096 bytes (4K).
|
||
|
||
Q. I'm getting a 'Stack Overflow!' message when I run my program.
|
||
How can I work around this?
|
||
A. You may increase the stack size by following the procedure above. Stack
|
||
overflows are usually caused by a large amount of local data or
|
||
recursive functions. You can decrease the amount of stack space
|
||
used by declaring your local variables static:
|
||
|
||
int main(void) int main(void)
|
||
{ {
|
||
char x[5000]; --> static char x[5000];
|
||
: :
|
||
} }
|
||
|
||
Of course, you should be aware that there are other effects
|
||
that the "static" keyword has, as applied here. See the Turbo C++
|
||
Programmer's Guide.
|
||
|
||
Q. My program comes up with the message 'Null pointer assignment'
|
||
after it terminates. What does this mean?
|
||
A. Before a small-data model Turbo C++ program returns to DOS, it will
|
||
check to see if the beginning of its data segment has been corrupted.
|
||
This message is to warn you that you have used uninitialized pointers
|
||
or that your program has corrupted memory in some other way.
|
||
|
||
Q. Why are .EXE files generated by TC.EXE larger than those
|
||
generated by TCC.EXE?
|
||
A. In the default configuration, TC.EXE includes debugging
|
||
information in the .EXE files that it creates, and TCC.EXE
|
||
does not. If you don't want to produce this debugging
|
||
information, you can shut it off in the Integrated
|
||
Development Environment by selecting Alt-D|S|N.
|
||
|
||
Q. Why do I get "declaration syntax error" messages on DOS.H?
|
||
A. You have set the "Ansi keywords only" option ON. Keep this option
|
||
OFF when using any keywords specific to Turbo C++. See the Turbo C++
|
||
Programmer's Guide for a list of keywords.
|
||
|
||
Q. I have a working program that dynamically allocates memory
|
||
using malloc() or calloc() in small data models (tiny, small,
|
||
and medium). When I compile this program in large data models
|
||
(compact, large, and huge), my program hangs.
|
||
A. Make sure that you have #include <alloc.h> in your program.
|
||
|
||
Q. I am linking my own assembly language functions with Turbo C++.
|
||
But the linker reports that all of my functions are undefined.
|
||
A. See answer above in the "Linker" section.
|
||
|
||
Q. My far pointers "wrap around" when they are incremented over 64K.
|
||
How do I reference a data object that is greater than 64K?
|
||
A. Use huge pointers.
|
||
|
||
Q. How do I interface Turbo C++ routines to a Turbo Pascal program?
|
||
A. See the example programs CPASDEMO.PAS and CPASDEMO.C on disk.
|
||
These files are packed in the file EXAMPLES.ARC. You will
|
||
need to UNPACK them before using them.
|
||
|
||
Q. How do I get Clipper to link with Turbo C++?
|
||
A. If you are having trouble, contact Nantucket Technical Support.
|
||
|
||
Q: I cannot locate the TCCNVT program which is referenced
|
||
in the documentation.
|
||
A: Due to last minute design considerations, this program was not
|
||
included on the shipping diskettes. The PRJ2MAK utility,
|
||
described in UTIL.DOC, has some of the same functionality.
|
||
|