为什么这些字符串不相等？他们是一样的吗？

Question

正在做一些 leet 代码，我想知道这两个字符串比较如何抛出错误，尝试以其他方式比较它们但没有成功。

    
int main(){
    
    std::cout<<std::boolalpha;
    std::string sa{"A man, a plan, a canal: Panama"};** // was trying to check if this was palindrome**

    for (int i{}; i < sa.size(); i++) { 

        if (!isalnum(sa[i]))//**removing non alpha chars
            sa[i] = '\0';**
        else sa[i] = tolower(sa[i]);
    }
    std::string se = sa;
    std::reverse(se.begin(), se.end());
    std::cout << (se == sa); **//turns out both strings are the same but this throws false **to the console

    return 0;
}

Answer 1

用'替换非字母数字字符