Question 1

What is dynamic memory allocation in C?

Accepted Answer

Dynamic memory allocation refers to allocating memory during the execution of a program (at runtime) rather than at compile-time. It provides flexibility for handling variable data sizes and allocating memory as needed.

Question 2

How is dynamic memory allocation different from static memory allocation?

Accepted Answer

In static memory allocation, the memory size is fixed and determined at compile-time, meaning it cannot be changed during runtime. In dynamic memory allocation, memory is allocated and deallocated during runtime, providing flexibility based on the program's requirements.

Question 3

What are the functions used for dynamic memory allocation in C?

Accepted Answer

The main functions used for dynamic memory allocation in C are:
malloc() – Allocates memory block.
calloc() – Allocates memory for an array and initializes all elements to zero.
realloc() – Resizes a previously allocated memory block.
free() – Frees the allocated memory.

Question 4

What is the difference between malloc() and calloc()?

Accepted Answer

malloc() allocates a block of memory but doesn’t initialize it, leaving it with random values (garbage).
calloc() allocates memory for an array and initializes all the memory to zero.

Question 5

How do you free dynamically allocated memory?

Accepted Answer

Dynamically allocated memory is freed using the free() function. It deallocates the memory and returns it to the system, preventing memory leaks.

Question 6

What happens if we forget to use free()?

Accepted Answer

If you forget to use free() after dynamically allocating memory, it can lead to memory leaks. Memory leaks occur when the program consumes memory but never releases it, potentially causing the system to run out of memory over time.

Question 7

Can we use free() on a pointer set to NULL?

Accepted Answer

Yes, calling free() on a pointer that is NULL is safe. It will have no effect and will not cause any errors.

Question 8

What is a memory leak, and how can it be avoided?

Accepted Answer

A memory leak occurs when dynamically allocated memory is not deallocated, causing the program to retain unnecessary memory. It can be avoided by ensuring that every malloc(), calloc(), or realloc() is matched with a corresponding free().

Question 9

What is fragmentation in dynamic memory allocation?

Accepted Answer

Fragmentation occurs when there are multiple small blocks of memory available but none large enough to satisfy a new memory allocation request. This is caused by frequent memory allocation and deallocation.

Question 10

What does realloc() do?

Accepted Answer

The realloc() function changes the size of a previously allocated memory block. It can expand or shrink the allocated memory based on the new size provided. If the new size is larger, it may move the contents to a new memory block and free the old one.

Dynamic Memory Allocation in C Programming

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