如何将CString转换为char *&？ [英] how to convert CString to char *&?

问题描述

在我的visual c ++项目中，我想在char *&中转换CString对象。如何执行它？

项目是使用UNICODE支持构建的

In my visual c++ project i want to convert a CString object in char *&. how to perform it?
project is build with UNICODE support

推荐答案

好的，所以你调用的函数需要一个char *类型的参数&放;.这可能意味着，它采用char *形式的字符串作为输入，但希望能够自由地分配新缓冲区并通过此参数返回（因此引用）。



不幸的是，这个函数想要一个char *&而不是const char *&。这意味着，该函数还保留修改传入的字符串的权限。这意味着，您必须为该字符串分配一个新缓冲区，并且不能使用CString对象的缓冲区。



这是我要做的：

Ok, so a function you call wants an argument of type char*&. That probably means, it takes a character string in the form of a char* as input, but wants to have the freedom of allocating a new buffer and return that via this parameter (therefore the reference).

Unfortunately the function wants to have a char*& and not a const char*&. That means, the function reserves also the right to modify the string you are passing in. That means, you must allocate a new buffer for that string and you cannot use the buffer of your CString object.

Here is what I would do:

CString myString ("abcdef");
...
char* pBuffer = new char[myString.GetLenght() + 1]; // +1 for the NULL byte
strcpy (pBuffer, myString);
char* pArg = pBuffer; // copy pBuffer, because OtherFunction might
                      // return a different buffer in pArg and would
                      // overwrite our pBuffer
OtherFunction (pArg);
...
... look at what OtherFunction has returned via pArg
...
delete [] pBuffer;
...
... possibly you will have to delete [] pArg too, depending on the
... interface of OtherFunction.

如你所见，这是一个非常丑陋和危险的界面，我会尽量避免这种结构。

As you see, this is an extremely ugly and dangerous interface and I would try to avoid such constructs whenever possible.

on-stack only代码:)：

The "on-stack only" code :) :

{
  CString cszTest(_T("abc"));

#ifdef _UNICODE
  USES_CONVERSION;
  const char* pCh1(T2A(cszTest));
#else
  const char* pCh1(cszTest);
#endif
  const char*& pCh2(pCh1);

  //..
}

// Actualy this argument is required by a function. That function is written by in another module.

另一个模块可以自己分配指针:)，

请阅读其文档，然后检查此变体：

Another modul may allocate the pointer by itself :) ,
please read its documentation and then check this variant:

{
  char* pChToBeAllocatedAndFilled(NULL);
  pModul->Call(pChToBeAllocatedAndFilled);

  CString cszResult(pChToBeAllocatedAndFilled); // convert it to UNICODE string

  // Warning !
  // Now we must know how the pointer has been allocated:

  //free(pChToBeAllocatedAndFilled); // or
  delete (pChToBeAllocatedAndFilled);
}

你好，



你不用担心*&，这意味着应该在该函数内修改给定指针中的数据。您只需将CString转换为char *并传递给该函数。但所有这些因素都取决于另一个模块的实现。

Hi,

You dont worry about "*&", it means the data in the given pointer should be modified inside that function. You just convert CString to char* and pass to that function. But all these factors depends on the "another module" implementation.

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