>>746
#include <stdio.h>

int main()
{
    const char *filename="yyy.txt";

    int count[26]={0}, i;
    char ch;
    char max_index=-1, max_value=0;

    FILE *fp;

    if ((fp=fopen(filename, "r"))==NULL)
        return 1;

    while( (ch=fgetc(fp)) != EOF)
    {
        if (ch>='a' && ch<='z')
        {
            count[ch-0x60]++;
        }
        else if (ch>='A' && ch<='Z')
        {
            count[ch-0x40]++;
        }
    }