Why Does Attempting to Convert char to wchar_t with mbstowcs() Lead to Unexpected Results?

How to Properly Convert char to wchar_t for Unicode Integration

Converting char strings to wchar_t is essential for integrating normal character strings into Unicode applications. One common approach is through the mbstowcs() function.

Original attempt:

The following code may seem like a straightforward implementation but unfortunately yields unexpected results:

<code class="c++">const wchar_t *GetWC(const char *c)
{
    const size_t cSize = strlen(c)+1;
    wchar_t wc[cSize];
    mbstowcs (wc, c, cSize);

    return wc;
}</code>

Delving Deeper:

The issue lies with the declaration of wc as a local variable. Upon function return, wc becomes deallocated, leaving the function with a pointer pointing to garbage memory.

Solution:

To resolve this, we allocate the memory for wc dynamically and return a pointer to it. The modified code below demonstrates this:

<code class="c++">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;
}</code>

Caveat:

It's crucial to note that the calling code is now responsible for deallocating the dynamically allocated memory to prevent memory leaks.

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