c++ string的+=和=区别？

#include<iostream>
#include<string>

int main() {
    std::string str1 = "Hello";
    std::string str2 = " World";
    str1 += str2;
    std::cout<< str1<< std::endl; // 输出 "Hello World"
    return 0;
}

#include<iostream>
#include<string>

int main() {
    std::string str1 = "Hello";
    std::string str2 = " World";
    str1 = str2;
    std::cout<< str1<< std::endl; // 输出 " World"
    return 0;
}