Dynamic Memory Allocation in C using malloc

Defined the topics:
1. Malloc
2.Calloc
3.Realloc

Every team will make report on the given topics in details and submit here. As this is a teamwork, group
members will work on one report.
1. Function of malloc(), calloc(),realloc()
2. Syntax of these 3 methods (With Explanation)
3. Apply these methods in code and explain.
4.Advantage, Disadvantage.

Answer:

1. Functions of malloc(), calloc(), and realloc()
 malloc():
Allocates a specified amount of memory during runtime and returns a pointer to the first byte of the
allocated memory. The memory is uninitialized.
 calloc():
Allocates memory for an array of elements, initializes all bytes to zero, and returns a pointer to the
allocated memory.
 realloc():
Changes the size of previously allocated memory block. It can be used to increase or decrease the
size of the memory allocated and may move the memory to a new location if necessary.

2. Syntax of These Methods
 malloc(size_t size)
Description: Allocates size bytes of memory.
Return Value: Returns a pointer to the allocated memory or NULL if the allocation fails.
 calloc(size_t num, size_t size)
Description: Allocates memory for an array of num elements, each of size bytes.
Return Value: Returns a pointer to the allocated memory or NULL if the allocation fails.
 realloc(void *ptr, size_t size)
Description: Resizes the memory block pointed to by ptr to size bytes. If ptr is NULL, it
behaves like malloc.
Return Value: Returns a pointer to the newly allocated memory or NULL if the allocation
fails. The original memory block is freed if the allocation fails.

3. Apply These Methods in Code
#include <stdio.h>
#include <stdlib.h>
int main() {
int *arr1;
arr1 = (int*)malloc(5 * sizeof(int));
if (arr1 == NULL) {
printf(“Memory allocation failed\n”);
return 1;
}
int *arr2;
arr2 = (int*)calloc(5, sizeof(int));
if (arr2 == NULL) {
printf(“Memory allocation failed\n”);
free(arr1);
return 1;
}
arr1 = (int*)realloc(arr1, 10 * sizeof(int)); // Resize to hold 10 integers
if (arr1 == NULL) {
printf(“Reallocation failed\n”);
free(arr2);
return 1;
}
free(arr1);
free(arr2);
return 0;
}

4. Advantages and Disadvantages
 malloc()
Advantages: Simple to use; allocates a specific amount of memory.
Disadvantages: Memory is uninitialized, which can lead to unpredictable behavior if accessed before initialization.
 calloc()
Advantages: Initializes allocated memory to zero, which can prevent issues with uninitialized data.
Disadvantages: Slightly slower than malloc() due to initialization.
 realloc()
Advantages: Allows dynamic resizing of memory, which can be more memory-efficient.
Disadvantages: May involve moving memory to a new location, which requires additional overhead; can lead to memory leaks if not handled properly.