Ask about how to change from unsigned char to char

I want to ask about how to change from unsigned char to char. This below is some part of my code which wrong. Do you know how to correct my code for changing unsigned char to char. Thank you very much.

code
.................................................. ...................................
CArray<unsigned char, unsigned char> m_data;
char* argv;
int k = 0;
for (i=0; i< m_data.GetSize(); i++)
{
argv[i] = m_data[i];
}
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ok, the first way this code is wrong is that you never allocated memory for char *argv. it is an uninitialized pointer. so you will have a memory access error. Second, once you have allocated the memory, your assignment probably needs to cast. as in the following:

argv[i] = (char*)m_data[i];

Have fun.