Difference between malloc and calloc functions
What is malloc?
Malloc stands for memory allocation, and it is a function in the C programming language that is used to dynamically allocate memory at runtime. It is used to provide memory to a program during its execution to store variables and data structures. Malloc function returns a pointer to the address of the block of memory allocated.
Examples of malloc:
Here is an example of using malloc to allocate memory for an integer:
“`
int *ptr;
ptr = (int*) malloc(sizeof(int));
“`
Uses of malloc:
The malloc function is used for the following purposes:
- Dynamic memory allocation
- Creating arrays
- Creating linked lists
- Allocating memory for structures
What is calloc?
Calloc also stands for continuous allocation, and it is a function in the C programming language that is used to dynamically allocate multiple blocks of memory at runtime. It is similar to malloc, but it initializes the allocated memory to zero. Calloc function returns a pointer to the starting address of the allocated memory block.
Examples of calloc:
Here is an example of using calloc to allocate memory for an array of integers:
“`
int *ptr;
ptr = (int*) calloc(5, sizeof(int));
“`
Uses of calloc:
The calloc function is used for the following purposes:
- Allocation of multiple elements in an array
- Allocation of memory for dynamic data structures like trees and graphs
- Initialization of dynamically allocated memory to zero
Differences between malloc and calloc functions:
| Difference Area | Malloc | Calloc |
|---|---|---|
| Memory Initialization | Memory content is not initialized | Memory content is initialized to zero |
| Arguments | Accepts only one argument (size in bytes) | Accepts two arguments (number of elements and size of each element in bytes) |
| Memory Content | Contains garbage values | Contains zeros |
| Efficiency | Relatively faster | Relatively slower due to initialization |
| Use of Memory | Does not change the initial value of memory | Set the initial value of memory to zero |
| Allocation | Allocates memory for a single block | Allocates memory for multiple blocks |
| Memory Reallocation | Does not support reallocation | Supports reallocation using realloc function |
| Failure | Returns NULL on failure | Returns NULL on failure |
| Overhead | Less overhead | More overhead due to zero initialization |
| Memory Usage | May lead to wastage of memory due to fragmentation | Less wastage of memory due to zero initialization |
Conclusion:
In summary, malloc and calloc functions are used for dynamic memory allocation in C, but they have some differences. Malloc does not initialize the allocated memory, while calloc initializes the memory to zero. Malloc allocates memory for a single block, while calloc allocates memory for multiple blocks. Calloc has a higher overhead due to zero initialization, but it results in less wastage of memory. Both functions return NULL on failure.
Knowledge Check:
- Which function initializes the allocated memory to zero?
a) Malloc
b) Calloc
c) Both
d) Neither
Answer: b) Calloc - How many arguments does malloc accept?
a) One
b) Two
c) Three
d) Depends on the size
Answer: a) One - Which function is relatively faster?
a) Malloc
b) Calloc
c) Both have the same speed
d) Depends on the size of the allocated memory
Answer: a) Malloc - … (continue with more questions)
