Hi I created a char* pointer and malloc a certain size to it. Then I pass this pointer to a function which fills up the memory allocated.
Now i want to free the memory allocated but I keep getting some error. Heap corruption detected
Here is what i did
the freeing part i did thisCode:char* buffer; buffer = (char*)malloc(100); fillupbuffer(&buffer);
and there comes the error.Code:free(buffer);
Why do you need to pass a char** to fillupbuffer when you have already allocated memory for the buffer? Normally, if you pass a char**, it means that fillupbuffer itself will be doing a malloc. I suggest that you show us the declaration of fillupbuffer. Also, check that you #include <stdlib.h> because the unnecessary cast of the return value of malloc would mask an error associated with failing to include that header.
Look up a C++ Reference and learn How To Ask Questions The Smart WayOriginally Posted by Bjarne Stroustrup (2000-10-14)
oh the fillupbuffer function basically looks like this
If I do the malloc inside the fill buffer function, how do I free it outside the function?Code:freebuffer(char** buffer) { uint16_t a= 1234; memcpy(*buffer,a,sizeof(uint16_t)); }
Yes i included stdlib.h already.
Sorry for the noobness
Since you don't need malloc there, just pass a char*.
It seems you renamed it
You probably want to pass the address of a, e.g.,
Of course, now fillupbuffer(&buffer) should be fillupbuffer(buffer). Incidentally, are you trying to fill the buffer with "1234" instead?Code:void fillupbuffer(char *buffer) { uint16_t a = 1234; memcpy(buffer, &a, sizeof(a)); }
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Oh hahaha sorry for the renaming, morning blues.
But if i declare a char* and allocate memory and pass the address of that pointer to a function, what advantages does it has?
Compared the above to declaring a char* and pass address of that pointer to function and allocating memory in that function,
and compared to just passing the address in.
If I have 2 memcpy actions, in which both copies to different memory addresses in the buffer, which of the above will be better?
Oh i actually have a lot of information to memcpy to the buffer, but its the concept which I am confused with.
If you take my suggestion of just having a char* parameter, your function is then more reusable: you can use it even if buffer is an actual array instead of a pointer. It is also typically easier to work with fewer levels of indirection. If you use a char** parameter and malloc from within the function, you are then constrained with working with just such a dynamic array.
This does not affect the choice.
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