Freeing memory necessary?

I was wondering if it's necessary to free the allocated memory in the following example:

Code:

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#include <stdio.h>

int main()
{
    char **data = malloc(sizeof(char *) * 5);
    if(data == NULL) {
        return 0;
    }

    int i;
    for(i = 0; i < 5; i++) {
        data[i] = malloc(sizeof(char) * 10);

        if(data[i] == NULL) {
            // Should I free memory here?
            return 0;
        }
    }

    return 0;
}

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Let's say the first two times memory gets allocated, so data[0] & data[1] are not NULL. Now if the third time malloc() returns NULL, should I first free the memory in data[0] & data[1] before terminating the program or is this unnecessary since the program quits immediatly after?

you should never NOT free the memory that your program allocates.
not freeing memory = memory leaks :) memory leak != good;

Quote:

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or is this unnecessary since the program quits immediatly after?

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There is no guarentee that the operating system will clean up after sloppy-written program fails to free memory. Some os do, and some don't.

>should I first free the memory in data[0] & data[1] before terminating
>the program or is this unnecessary since the program quits immediatly after?
Yes, if only because it's a good habit to get into. Chances are good that you're using an operating system that frees resources allocated to your process when the process terminates, so the memory leak argument isn't quite as big of an issue as some people would have you think. However, good programs have a tendency to be reused, so your program could become just another module in a larger program. At that point the memory leak could become very serious. Therefore, it's best to always free memory you allocate.