c语言实现统计字符串中元音字母的个数

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

int main()
{
    char str[100];
    int vowels = 0, i;

    printf("请输入一个字符串：");
    gets(str);

    for (i = 0; str[i] != '\0'; ++i) {
        if (str[i] == 'a' || str[i] == 'e' || str[i] == 'i' ||
            str[i] == 'o' || str[i] == 'u' || str[i] == 'A' ||
            str[i] == 'E' || str[i] == 'I' || str[i] == 'O' ||
            str[i] == 'U') {
            ++vowels;
        }
    }

    printf("字符串中元音字母的个数为：%d", vowels);
    return 0;
}

--相关问题--:
1. 如何统计字符串中某个字符的个数？
2. 如何判断一个