Error when freeing memory (allocated with realloc)

**matsp** · 01-02-2008

But WHERE did the "number" variable get produced, as in: what does it actually point to? Something allocated with malloc(), or something else? Show us the code that calls add_number().

You do realize that you are not writing your "number" content into the memory allocated in the second code-snippet I quoted, but rather just overwriting the pointer itself.

If you EVER free something that wasn't allocated by malloc/realloc, then you will get undefined behaviour - such as what you are seeing right now?

--
Mats

**ZuK** · 01-02-2008

Originally Posted by svdrjeug

The c->numbers[0..2] are all allocated in this piece of code

Code:

numbers = malloc(sizeof(char**));
	for(i=0; i < 3; i++) {
		numbers[i] = malloc(sizeof(char*));
		for(j=0; j < 1; j++)
			numbers[i][j] = malloc(15*sizeof(char));
	}

I think this piece is correct.

No that's not correct. True you allocate the space for 3 pointers but you store them where there is only spce for 1 pointer ( numbers is only the size of a single pointer ).
Kurt

**iMalc** · 01-02-2008

Originally Posted by svdrjeug

I have tried to make some changes as suggested, but they didn't solve the problem, so I've put my original code back.

Big mistake.

Let me rephrase my previous comments:
You should not use char*** numbers;
You are not getting the memory allocation right anyway, so switch to something that is easier to get correct such as char *numbers[3];
Yes that means you have to change a lot of other code as well. You need to do this to make a working program.

Although this line is wrong for other reasons as well, it must be a strcpy:

Code:

		c->numbers[0][c->numbers_size[0]-1] = number;

**svdrjeug** · 01-03-2008

Originally Posted by ZuK

No that's not correct. True you allocate the space for 3 pointers but you store them where there is only spce for 1 pointer ( numbers is only the size of a single pointer ).
Kurt

Yeah, you were right! I changed to

Code:

numbers = malloc(3*sizeof(char**));

and it works perfect!

Thank you everybody for the quick replies and tips. I will change my implementation now, as suggested by you.

Steven

Thread: Error when freeing memory (allocated with realloc)

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