题解 | #字符个数统计#

#include <stdio.h>
#include <string.h>

int main() {
    char arr[502] = {-1};
    memset(arr, -1, 502);

    //去除末尾的 "\r\n"
    fgets(arr, 502, stdin);
    arr[strcspn(arr,"\n")] = -1;
    arr[strcspn(arr,"\r")] = -1;
    //scanf("%s", arr);

    char flag[128] = {0};
    int i =0;
    for (i = 0; ; i++) {
        //判断是否到达了末尾
        if (arr[i] == -1) {
            break;
        }

        flag[arr[i]] = 1;
        //printf("i:%d\n", i);
    }

    int ret = 0;
    for (i = 0; i < 128; i++) {
        if (flag[i] == 1) {
            ret++;
        }
    }
    printf("%d", ret);
    return 0;
}