52 lines
1.4 KiB
C++
52 lines
1.4 KiB
C++
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/* ungetc and ungetch - reverse getc, getch */
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/* Copyright (c) Mix Software 1988 */
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/* Replace character in buffer. Will always work for at least
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one character. For buffered files, ungetc can be called
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mulitiple times until the beginning of the buffer is reached.
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Returns EOF if unable to save character.
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*/
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ungetc(c,fp)
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int c;
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FILE *fp;
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{
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if (c != EOF) {
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fp->file.eofflag = 0;
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if (fp->file.bufr) {
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if (fp->file.bufr == fp->file.ptr) {
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if (fp->file.count == 0) {
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*fp->file.ptr = c;
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fp->file.count = 1;
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}
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else return EOF;
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}
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else {
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*(--fp->file.ptr) = c;
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++fp->file.count;
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}
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}
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else {
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fp->file.ptr = &fp->file.ungetch;
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*fp->file.ptr = c;
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fp->file.count = 1;
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}
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}
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return c;
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}
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/* ------------------------------------------------------------ */
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/* Reverse action of getch (unbuffered input from keyboard).
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Only one character can be saved; returns EOF if unable to
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save the character.
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*/
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ungetch(c)
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int c;
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{
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extern char _ungetch;
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if (_ungetch != EOF) return EOF;
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_ungetch = c;
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return c;
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}
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int _ungetch = EOF;
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