C Memory Management

malloc, calloc, realloc and free.

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Memory can be allocated while the program runs (on the heap) using <stdlib.h>:

malloc(size): allocate memory (contents are random).
calloc(n, size): allocate and set to zero.
realloc(ptr, newSize): resize.
free(ptr): give the memory back.

Always check that allocation succeeded (the pointer is not NULL), and free every block exactly once. Forgetting causes memory leaks.

Key Takeaways: C Memory Management

Mastering C Memory Management helps you write clean and reliable C code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.

C Memory Management Code Example

#include <stdio.h>
#include <stdlib.h>

int main() {
    int n = 5;
    int *nums = malloc(n * sizeof(int));
    if (nums == NULL) return 1;

    for (int i = 0; i < n; i++) nums[i] = (i + 1) * 10;

    nums = realloc(nums, 6 * sizeof(int));
    nums[5] = 60;

    for (int i = 0; i < 6; i++) printf("%d ", nums[i]);
    printf("\n");

    free(nums);
    return 0;
}

Output