How to convert char to wchar t

Question

I ve tried implementing a function like this  but unfortunately it doesn t work   const wchar t  GetWC const char  c        const size t cSize   strlen c  1      wchar t wc cSize       mbstowcs  wc  c  cSize        return wc      My main goal here is to be able to integrate normal char strings in a Unicode application  Any advice you guys can offer is greatly appreciated

User · Answer

I did something like this  The first 2 zeros are because I don t know what kind of ascii type things this command wants from me  The general feeling I had was to create a temp char array  pass in the wide char array  boom  it works  The  1 ensures that the null terminating character is in the right place    char tempFilePath MAX PATH     I want to convert this to wide chars    int len   strlen tempFilePath       Converts the path to wide characters     int needed   MultiByteToWideChar 0  0  tempFilePath  len   1  strDestPath  len   1

User · Answer

In your example  wc is a local variable which will be deallocated when the function call ends  This puts you into undefined behavior territory   The simple fix is this   const wchar t  GetWC const char  c        const size t cSize   strlen c  1      wchar t  wc   new wchar t cSize       mbstowcs  wc  c  cSize        return wc      Note that the calling code will then have to deallocate this memory  otherwise you will have a memory leak

User · Answer

Use a std  wstring instead of a C99 variable length array  The current standard guarantees a contiguous buffer for std  basic string  E g    std  wstring wc  cSize  L       mbstowcs   amp wc 0   c  cSize      C   does not support C99 variable length arrays  and so if you compiled your code as pure C    it would not even compile   With that change your function return type should also be std  wstring   Remember to set relevant locale in main   E g   setlocale  LC ALL         Cheers  amp  hth

User · Answer

You re returning the address of a local variable allocated on the stack  When your function returns  the storage for all local variables  such as wc  is deallocated and is subject to being immediately overwritten by something else   To fix this  you can pass the size of the buffer to GetWC  but then you ve got pretty much the same interface as mbstowcs itself  Or  you could allocate a new buffer inside GetWC and return a pointer to that  leaving it up to the caller to deallocate the buffer

User · Answer

Your problem has nothing to do with encodings  it s a simple matter of understanding basic C    You are returning a pointer to a local variable from your function  which will have gone out of scope by the time anyone can use it  thus creating undefined behaviour  i e  a programming error    Follow this Golden Rule   If you are using naked char pointers  you re Doing It Wrong   Except for when you aren t     I ve previously posted some code to do the conversion and communicating the input and output in C   std  string and std  wstring objects

User · Answer

const char  text char    example of mbstowcs   size t length   strlen text char      Example of usage  mbstowcs   std  wstring text wchar length  L          pragma warning  disable   4996     Or add to the preprocessor   CRT SECURE NO WARNINGS mbstowcs  amp text wchar 0   text char   length     Example of usage  mbstowcs s   Microsoft suggest to use  mbstowcs s  instead of  mbstowcs    Links   Mbstowcs example  mbstowcs s   mbstowcs s l  wchar t text wchar 30    mbstowcs s  amp length  text wchar  text char  length

[c++] How to convert char* to wchar_t*?

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