free() Function in C Library With Examples Last Updated : 29 May, 2023 Comments Improve Suggest changes Like Article Like Report The free() function in C is used to free or deallocate the dynamically allocated memory and helps in reducing memory wastage. The C free() function cannot be used to free the statically allocated memory (e.g., local variables) or memory allocated on the stack. It can only be used to deallocate the heap memory previously allocated using malloc(), calloc() and realloc() functions. The free() function is defined inside <stdlib.h> header file. C free() FunctionSyntax of free() Function in Cvoid free(void *ptr);Parametersptr is the pointer to the memory block that needs to be freed or deallocated.Return ValueThe free() function does not return any value.Examples of free()Example 1: The following C program illustrates the use of the calloc() function to allocate memory dynamically and free() function to release that memory. C // C program to demonstrate use of // free() function using calloc() #include <stdio.h> #include <stdlib.h> int main() { // This pointer ptr will hold the // base address of the block created int* ptr; int n = 5; // Get the number of elements for the array printf("Enter number of Elements: %d\n", n); scanf("%d", &n); // Dynamically allocate memory using calloc() ptr = (int*)calloc(n, sizeof(int)); // Check if the memory has been successfully // allocated by calloc() or not if (ptr == NULL) { printf("Memory not allocated \n"); exit(0); } // Memory has been Successfully allocated using calloc() printf("Successfully allocated the memory using " "calloc(). \n"); // Free the memory free(ptr); printf("Calloc Memory Successfully freed."); return 0; } OutputEnter number of Elements: 5 Successfully allocated the memory using calloc(). Calloc Memory Successfully freed.Example 2: The following C program illustrates the use of the malloc() function to allocate memory dynamically and free() function to release that memory. C // C program to demonstrate use of // free() function using malloc() #include <stdio.h> #include <stdlib.h> int main() { // This pointer ptr will hold the // base address of the block created int* ptr; int n = 5; // Get the number of elements for the array printf("Enter number of Elements: %d\n", n); scanf("%d", &n); // Dynamically allocate memory using malloc() ptr = (int*)malloc(n * sizeof(int)); // Check if the memory has been successfully // allocated by malloc() or not if (ptr == NULL) { printf("Memory not allocated \n"); exit(0); } // Memory has been Successfully allocated using malloc() printf("Successfully allocated the memory using " "malloc(). \n"); // Free the memory free(ptr); printf("Malloc Memory Successfully freed."); return 0; } OutputEnter number of Elements: 5 Successfully allocated the memory using malloc(). Malloc Memory Successfully freed. Comment More infoAdvertise with us Next Article free() Function in C Library With Examples kamleshjoshi18 Follow Improve Article Tags : C Language C-Dynamic Memory Allocation c-memory-management Similar Reads C Programming Language Tutorial C is a general-purpose mid-level programming language developed by Dennis M. Ritchie at Bell Laboratories in 1972. It was initially used for the development of UNIX operating system, but it later became popular for a wide range of applications. Today, C remains one of the top three most widely used 5 min read Dynamic Memory Allocation in C using malloc(), calloc(), free() and realloc() In C, a variable defined in a function is stored in the stack memory. The requirement of this memory is that it needs to know the size of the data to memory at compile time (before the program runs). 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