count_ch.c

里面包含很多c语言的源码

/* Counts the number of occurrences
   of each character in a file. */
#include <stdio.h>
#include <stdlib.h>
int file_exists(char *filename);
int main( void )
{
     char ch, source[80];
     int  index;
     long count[127];
     FILE *fp;

     /* Get the source and destination filenames. */
     fprintf(stderr, "\nEnter source file name: ");
     gets(source);

     /* See that the source file exists. */
     if (!file_exists(source))
     {
        fprintf(stderr, "\n%s does not exist.\n", source);
        exit(1);
     }
     /* Open the file. */
     if ((fp = fopen(source, "rb")) == NULL)
     {
        fprintf(stderr, "\nError opening %s.\n", source);
        exit(1);
     }
     /* Zero the array elements. */
     for (index = 31; index < 127 ; index++)
        count[index] = 0;

     while ( 1 )
     {
        ch = fgetc(fp);
        /* Done if end of file */
        if (feof(fp))
            break;
        /* Count only characters between 32 and 126. */
        if (ch > 31 && ch < 127)
            count[ch]++;
     }
     /* Display the results. */
     printf("\nChar\t\tCount\n");
     for (index = 32; index < 127 ; index++)
        printf("[%c]\t%d\n", index, count[index]);
     /* Close the file and exit. */
     fclose(fp);
     return(0);
}
int file_exists(char *filename)
{
   /* Returns TRUE if filename exists,
      FALSE if not. */
   FILE *fp;
   if ((fp = fopen(filename, "r")) == NULL)
       return 0;
   else
   {
       fclose(fp);
       return 1;
   }
}