为什么我们不能删除已初始化的指针？ [英] Why can't we delete an initialized pointer?

问题描述

我用一些随机值初始化一个 char 指针，当我试图删除它时，我无法。为什么呢？

I am initializing a char pointer with some random values, and when I am trying to delete it, I am unable to. Why is that?

这里是我在做什么：

int main()
{
    char *s = new char[50];    // I know there is no reason for using new if initializing, but in order to use delete we need to allocate using new.
    s = "Harry";
    delete s;
    return 0;
}

推荐答案

如果你真的想练习用指针，你需要修复你的代码。主要的问题是你试图分配字符串文字（这是 const char [6] 在这里）指针 s 然后尝试修改它通过调用delete调用未定义的行为（ UB ）。

If you really want to practice with pointer, you need to fix your code. The main problem is you are trying to assign string literal( which is const char[6] in here) to pointer s then try to modify it by calling delete which invoke undefined behavior(UB).

char *s = new char[50];    
strcpy(s, "Harry");     // don't assign string literal to it
                        // re-assign pointer to string literal,
                        // lost pre-allocated memory position and caused delete to fail 
                        // it's UB to modify string literal
delete []s;             // new[]/delete[], new/delete need to be called in pair. 

只需使用 std :: string

#include <string>
std::string s("Harry"); // no worries

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