统计文本中字母的频次（不区分大小写）

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#define _CRT_SECURE_NO_WARNINGS #include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX_NUM 10240   void count(char* n) {     int i = 0, s[26] = { 0 };     while (n[i] != NULL)     {         if (n[i] >= 'A' && n[i] <= 'Z')         {             n[i] += 32;             s[n[i] - 'a']++;             i++;         }         else if (n[i] >= 'a' && n[i] <= 'z')         {             s[n[i] - 'a']++;             i++;         }         else             i++;     }       for (i = 0; i < 26; i++)     {         printf("%c出现：%d次\n", (char)(i + 'a'), s[i]);     } } int main() {     char buf[MAX_NUM];          //字符缓冲区     FILE* fp;     //fopen("doc.txt", "r+")，读取文本中的内容     if ((fp = fopen("doc.txt", "r+")) == NULL) {         perror("the file fail to read");         exit(1);     }     while (!feof(fp) && !ferror(fp)) {  //文件读取结束或出错则退出    //while(fgets(buf,MAX_NUM,fp) != NULL)         fgets(buf, MAX_NUM, fp);//每次读取一行或者MAX_NUM个字符         printf("内容为：%s \n", buf);         count(buf);     }     fclose(fp);             //关闭文件     return 0; }