calloc function - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the calloc function do in C?

calloc allocates memory for an array of elements, initializes all bytes to zero, and returns a pointer to the allocated memory.

beginner

What is the difference between malloc and calloc?

malloc allocates memory but leaves it uninitialized. calloc allocates memory and initializes all bytes to zero.

beginner

How do you use calloc? Provide the function signature and explain parameters.

Signature: void *calloc(size_t num, size_t size);

num: number of elements to allocate.<br>size: size in bytes of each element.

beginner

What should you always do after using calloc to avoid memory leaks?

Always use free() to release the allocated memory when it is no longer needed.

beginner

What happens if calloc fails to allocate memory?

calloc returns NULL. You should always check the returned pointer before using it.

What does calloc(5, sizeof(int)) do?

A Frees memory allocated for 5 integers.

B Allocates memory for 5 integers but leaves it uninitialized.

C Allocates memory for 1 integer of size 5 bytes.

D Allocates memory for 5 integers and initializes all to zero.

calloc allocates memory for the number of elements (5) times the size of each element (sizeof(int)) and initializes all bytes to zero.

Which function initializes allocated memory to zero?

A calloc

B realloc

C malloc

D free

calloc initializes all allocated memory bytes to zero, unlike malloc.

What should you check after calling calloc?

A If the pointer is <code>NULL</code> to confirm allocation success.

B If the pointer is negative.

C If the pointer points to a string.

D If the pointer is an integer.

Always check if the pointer returned by calloc is NULL to ensure memory was allocated.

What happens if you forget to call free on memory allocated by calloc?

A Memory is automatically freed.

B Memory leak occurs, wasting memory.

C Program crashes immediately.

D Memory is doubled.

Not freeing allocated memory causes memory leaks, which waste system resources.

Which header file must be included to use calloc?

A <code>&lt;stdio.h&gt;</code>

B <code>&lt;string.h&gt;</code>

C <code>&lt;stdlib.h&gt;</code>

D <code>&lt;math.h&gt;</code>

calloc is declared in <stdlib.h>.

Explain how calloc works and why it might be preferred over malloc.

Think about what happens to the memory bytes after allocation.

Describe the steps you should take after calling calloc in a program.

Consider safety and resource management.