字符串小技巧

char s[100];

int main() {
    strcpy(s, "123");
    cout << atoi(s) << endl;    //atol同atoi

    strcpy(s, "12.3");
    cout << atof(s) << endl;    //没有atolf
    
    strcpy(s, "12345678987654321");
    cout << atoll(s) << endl;

    return 0;
}