DeAllocating Memory

DeAllocating Memory

• In C, memory allocated dynamically using functions like malloc, calloc, or realloc should be deallocated when it is no longer needed to prevent memory leaks.

• Memory deallocation is performed using the free function from the <stdlib.h> header.

Example

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

int main() {
    // Allocate memory for an array of integers
    int* dynamicArray = malloc(5 * sizeof(int));

    if (dynamicArray == NULL) {
        printf("Failed to allocate memory.\n");
        return 1; // Error handling
    }

    // Use the dynamically allocated memory

    // Deallocate the memory when done
    free(dynamicArray);

    return 0;
}

Explanation:

• We allocate memory for an array of integers using malloc.
• After using the dynamically allocated memory, we deallocate it using free.
• The free function releases the memory back to the system, making it available for reuse.

Key points regarding memory deallocation:

• The argument passed to free must be a pointer to the memory block that was previously allocated using malloc, calloc, or realloc.

• Passing any other pointer or a pointer that has already been freed results in undefined behavior.

• After calling free, the memory block should no longer be accessed. Any attempts to access freed memory may lead to bugs or crashes.

• Calling free on a NULL pointer is safe and has no effect.

• Memory deallocation should be performed for each dynamically allocated block individually. If multiple memory blocks were allocated, each one should be deallocated separately.

• It's a good practice to set the pointer to NULL after freeing the memory to avoid mistakenly accessing freed memory.

int* dynamicArray = malloc(5 * sizeof(int));
// Use the dynamically allocated memory

free(dynamicArray);
dynamicArray = NULL; // Set the pointer to NULL