39 lines
866 B
C
39 lines
866 B
C
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/* ungetc example */
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#include <stdio.h>
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void trace_file(FILE* f, char* cmt);
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int main ()
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{
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FILE * pFile;
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int c;
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char buffer [256];
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pFile = fopen ("myfile.txt","rt");
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if (pFile==NULL) perror ("Error opening file");
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else while (!feof (pFile)) {
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trace_file(pFile, "1");
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c=getc (pFile);
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trace_file(pFile, "before ungetc");
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if (c == EOF) break;
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if (c == '#') ungetc ('@',pFile);
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else ungetc (c,pFile);
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trace_file(pFile, "after");
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if (fgets (buffer,255,pFile) != NULL)
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puts (buffer);
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else break;
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}
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return 0;
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}
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void trace_file(FILE* f, char* cmt)
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{
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printf("%s[%s]\n", cmt, f->buffer);
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printf("mode=%0X, filesize=%d, filepos=%d\n", f->mode, f->filesize, f->filepos);
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printf("ungetc=%d, buffer_start=%d, buffer_end=%d\n", f->ungetc_buf, f->buffer_start, f->buffer_end);
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}
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