c++ 忽略大小写比较两个字符串的前n哥字符 strncasecmp

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

int main(){
    char *a = "aBcDeF";
    // char *b = "AbCdEf";
    char *b = "A";
    if(!strncasecmp(a, b, 3))    // 注意此处存在符号“!”
    {
        printf("%s =%s\n", a, b);
    }
    return 0;
}