使用后需要删除 CString 以释放内存吗?

2022-01-12 00:00:00 visual-c++ c++ mfc cstring

如果我使用这样的 CString:

If I am using a CString like this:

void myFunc(char *str)
{
  CString s(str);
  // Manipulate other data with CString
  // ...
  // Finished

  // Should I somehow delete 's' here to avoid a memory leak?
}

一旦函数超出范围,字符串是否会被删除?

Is the string erased once the function goes out of scope?

另外,我知道 new 关键字分配内存,如果我构造一个没有 new 关键字的对象,内存仍然分配吗?我的直觉告诉我是的,但我想验证一下.

Also, I know that the new keyword allocates memory, if I construct an object without the new keyword, is memory still allocated? My intuition tells me yes, but I would like to verify.

例如

CString *asdf = new CString("ASDF");
// same as?
CString asdf("ASDF"); 

推荐答案

new 在 heap 上分配内存,所以

new allocates memory on the heap, so

CString *asdf = new CString("ASDF");

在堆上分配一个 CString 并将指向它的指针分配给 asdf.在调用 delete asdf 之前,不会释放该内存,也不会调用 asdf 的析构函数.

Allocates a CString on the heap and assigns a pointer to it to asdf. That memory will not be freed, nor will the destructor of asdf be called until you call delete asdf.

没有new,你在stack上进行分配,所以

Without new, you are allocating on the stack, so

CString asdf("ASDF");

分配栈内存,asdf代表.当堆栈展开时(如从函数返回时),此内存会自动回收,并且 asdf 的析构函数会在超出范围时自动调用.

allocates stack memory, which asdf represents. This memory is automatically reclaimed when the stack is unwound (as in when you return from a function) and the destructor of asdf is automatically called when it goes out of scope.

另外,CString 会清理自己的资源,所以如果 CString 对象被清理(如果它在堆栈上则超出范围,如果它在堆栈上则被删除)堆),它使用的资源也会被清理.

Also, CString cleans up its own resources, so if the CString object is cleaned up (goes out of scope if it's on the stack or is deleted if it's on the heap), the resources it uses will also be cleaned up.

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