C++ 中的字符串分配:为什么这样做? [英] string allocation in C++: why does this work?

问题描述

void changeString(const char* &s){
    std::string str(s);
    str.replace(0, 5, "Howdy");
    s = str.c_str();
}

int main() {
    const char *s = "Hello, world!";
    changeString(s);
    std::cout << s << "\n";
    return 0;
}

当我运行这段代码时，它打印出你好，世界！"我认为 str 在 changeString 退出时会被破坏.我是否遗漏了 std::string 的分配方式?

When I run this code, it prints "Howdy, world!" I would think that str gets destroyed when changeString exits. Am I missing something with the way std::string gets allocated?

推荐答案

是的，str被销毁了；但字符串的内存没有被清除；您的s"指针指向空闲但未清除的内存.非常危险.

Yes, str is destroyed; but the memory of the string isn't cleared; your "s" pointer point to a free but non cleared memory. Very dangerous.

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