ungetc.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 21 行

#include <stdio.h>
#include <ctype.h>

void main()
  {
    FILE *fp;
    int c;
    long value;

    fp = fopen( "file", "r" );
    value = 0;
    c = fgetc( fp );
    while( isdigit(c) ) {
        value = value*10 + c - '0';
        c = fgetc( fp );
    }
    ungetc( c, fp ); /* put last character back */
    printf( "Value=%ld\n", value );
    fclose( fp );
  }