76 lines
1.8 KiB
Plaintext
76 lines
1.8 KiB
Plaintext
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(* Version 1.10, Nov 1984 *)
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DEFINITION MODULE RealInOut;
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(*
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Terminal input/output of REAL values
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The implementation of this module uses the procedures
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'ReadString' and 'WriteString' of module 'InOut' for
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reading and writing of REAl values. Therefore,
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redirection of i/o through 'InOut' applies, too.
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From the book 'Programming in Modula-2' by Prof.
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N. Wirth.
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*)
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EXPORT QUALIFIED
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ReadReal, WriteReal, WriteRealOct, Done;
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VAR Done: BOOLEAN;
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PROCEDURE ReadReal (VAR x: REAL);
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(*
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- Read a REAL from the terminal.
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out: x the number read.
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The range of representable valid real numbers is:
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1.0E-307 <= ABS(r) < 1.0E308
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The syntax accepted for input is:
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realnumber = fixedpointnumber [exponent].
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fixedpointnumber = [sign] {digit} [ '.' {digit} ].
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exponent = ('e' | 'E') [sign] digit {digit}.
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sign = '+' | '-'.
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digit = '0'|'1'|'2'|'3'|'4'|'5'|'6'|'7'|
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'8'|'9'.
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The following numbers are legal representations of one
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hundred: 100, 10E1, 100E0, 1000E-1, E2, +E2, 1E2, +1E2,
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+1E+2, 1E+2 .
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At most 15 digits are significant, leading zeros not
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counting. Input terminates a control character or space.
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DEL or BS is used for backspacing
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The variable 'Done' indicates whether a valid number was
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read.
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*)
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PROCEDURE WriteReal (x: REAL; n: CARDINAL);
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(*
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- Write a REAL to the terminal, right-justified.
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in: x number to write,
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n minimum field width.
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If fewer than n characters are needed to represent x,
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leading blanks are output. At least 10 characters are
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needed to write any REAL number.
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*)
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PROCEDURE WriteRealOct (x: REAL);
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(*
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- Write a REAL to terminal, as four words in octal form
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in: x number to write,
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*)
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END RealInOut.
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