Freeing malloc will not erase char data

Question

I made a smaller scenario of my bigger problem. What I try to do is pass a string to a function which will make a new string out of it. However I ran into some problems.

Answer 1

You should clear content of buf[1024] each iteration.

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UPDATE

Because buf[1024] will not be zero-ed automatically when allocated on the stack. And you choose strcat to concatenate two string, which will find a \0-terminate. Thus if buf contains some default value, it will introduce obfuscated output.

Use buf[1024] = ""; to allocate a buffer will correct the output.