CODEWITHSUNDEEP
memory-managementc++-cli
AndrewL
AndrewL

Reputation: 3326

Heap corruption detected error when attempting to free pointer

I'm pretty new to C++ and have run into a problem which I have not been able to solve. I'm trying to convert a System::String to a wchar_t pointer that I can keep for longer than the scope of the function. Once I'm finished with it, I want to clean it up properly. Here is my code:

static wchar_t* g_msg;

void TestConvert()
{
    pin_ptr<const wchar_t> wchptr = PtrToStringChars("Test");
    g_msg = (wchar_t*)realloc(g_msg, wcslen(wchptr) + 1);
    wcscpy(g_msg, wchptr);

    free (g_msg); // Will be called from a different method
}

When the free is called, I'm getting "HEAP CORRUPTION DETECTED: after Normal block (#137) at 0x02198F90."

Why would I be getting this error?

Andrew L

Upvotes: 1

Views: 2941

Answers (2)

Timo
Timo

Reputation: 5176

I think the you're allocating too small memory block for the string. Each character takes 2 bytes (in MSVC) because it's a wide string:

g_msg = (wchar_t*)realloc(g_msg, (wcslen(wchptr) + 1)*sizeof(wchar_t));

Upvotes: 5

Puppy
Puppy

Reputation: 146968

System::String is a managed string class, not a C++ string class. You need to convert to a std::wstring, which manages it's own memory, not a const wchar_t*.

Upvotes: 0

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