C语言 统计文本文件a.txt中小写英文字母的出现次数

#include<stdio。h>#include<string。h>int add(char *str,char *substr)//str c程序{int i,s=0,j;    for(i=0;i<strlen(str);i++)    {        for(j=0;j<strlen(substr);j++)        {            if(str[i+j]!=substr[j])                break;        }        if(substr[j]==0)            s++;    }    return s;}void main(){FILE *fp;char str[10000],substr[100][3]={"a","b" ,"c" ,"d","e","f","g","h","i","j","k","l","m","n","o", "p","q", "r", "s", "t", "u", "v", "w", "x","y","z"};    int j,i,s=0;if((fp=fopen("a。txt","r"))==NULL){printf("can not open the file\n");return;}while(!feof(fp)){fgets(str,500,fp);   for(i=0;i<26;i++){s=add(str,substr[i])+s;}}    printf("该程序小写字母一共有%d个",s);}fclose(fp);）