Free Function

The Free function releases a block of memory of at least 8 bytes that has been allocated by one of the heap allocation functions (malloc, calloc, or realloc). Attempting to free an invalid pointer (a pointer not allocated by these functions, or a pointer already freed) can lead to heap corruption.

After calling Free, the pointer ptr will point to a deallocated memory location. It is good practice to set the pointer to NULL immediately after freeing the memory to prevent accidental use of the dangling pointer.

This function is typically part of the standard C runtime library and is used extensively in C and C++ programming for dynamic memory management.

Example

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

int main() {
    char *buffer;

    // Allocate memory for 100 characters
    buffer = (char *)malloc(100 * sizeof(char));
    if (buffer == NULL) {
        perror("Failed to allocate memory");
        return 1;
    }

    // Use the allocated memory...
    printf("Memory allocated successfully.\n");
    sprintf(buffer, "This is a test string.");

    // Free the allocated memory
    free(buffer);
    printf("Memory freed.\n");

    // It's good practice to set the pointer to NULL
    buffer = NULL;

    // Attempting to free NULL does nothing
    free(buffer);

    return 0;
}