c++判断两个字符串是否相等

在C++中判断两个字符串是否相等可以使用字符串比较函数`strcmp()`，该函数接受两个字符串参数，如果两个字符串相等则返回0，否则返回非0值。示例代码如下：

#include <iostream>
#include <cstring>
using namespace std;

int main() {
    char str1[] = "Hello";
    char str2[] = "world";
    char str3[] = "Hello";

    if (strcmp(str1, str2) == 0) {
        cout << "str1 and str2 are equal" << endl;
    } else {
        cout << "str1 and str2 are not equal" << endl;
    }

    if (strcmp(str1, str3) == 0) {
        cout << "str1 and str3 are equal" << endl;
    } else {
        cout << "str1 and str3 are not equal" << endl;
    }

    return 0;
}

输出结果为：

str1 and str2 are not equal
str1 and str3 are equal

另外，如果使用`std::string`类型存储字符串，则可以使用`==`运算符判断两个字符串是否相等，示例代码如下：

#include <iostream>
#include <string>
using namespace std;

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

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

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

    return 0;
}

输出结果为：

str1 and str2 are not equal
str1 and str3 are equal