C++ string比较

C++中可以使用`==`运算符来比较两个字符串是否相等，例如：

#include <iostream>
#include <string>

using namespace std;

int main() {
    string str1 = "hello";
    string str2 = "world";
    string str3 = "hello";

    if (str1 == str2) {
        cout << "str1 is equal to str2" << endl;
    } else {
        cout << "str1 is not equal to str2" << endl;
    }

    if (str1 == str3) {
        cout << "str1 is equal to str3" << endl;
    } else {
        cout << "str1 is not equal to str3" << endl;
    }

    return 0;
}

输出结果为：

str1 is not equal to str2
str1 is equal to str3

注意，C++中的字符串比较是区分大小写的。