Memory Management

Which header file is required for dynamic memory functions like malloc()?

• <stdlib.h>

• <malloc.h>

• <stdio.h>

• <memory.h>

Answer explanation

All dynamic memory functions like malloc(), calloc(), realloc(), and free() are declared in <stdlib.h>.

Which function is used to dynamically allocate memory in C?

• alloc()

• malloc()

• memory()

• free()

Answer explanation

malloc() allocates memory in bytes and returns a pointer to the first byte.

What will malloc() return if it fails to allocate memory?

• -1

• 0

• NULL

• Error

Answer explanation

On failure, malloc() returns NULL

Which function is used to free dynamically allocated memory?

• delete()

• dispose()

• free()

• clear()

What is the output of the following code?

int ptr = (int )malloc(sizeof(int));

*ptr = 5;

printf("%d", *ptr);

• Compilation error

• Address of ptr

• 5

• Garbage Value

Answer explanation

Memory is allocated, value 5 is assigned and printed correctly.

Which function initializes memory to zero?

• malloc()

• calloc()

• realloc()

• free()

Answer explanation

calloc() allocates memory and sets all bytes to zero.

What is the purpose of realloc()?

• To allocate memory

• To reassign memory

• To change the size of previously allocated memory

• To remove memory

Answer explanation

realloc() resizes a memory block that was previously allocated.

What happens if you call free() twice on the same pointer?

• Nothing

• Memory leaks

• Undefined behavior / crash

• Memory increases

Answer explanation

Calling free() twice on the same pointer can cause crashes or bugs.

What is a memory leak?

• When memory is freed twice

• When unused memory is not released

• When stack memory is overloaded

• When memory is corrupted

Answer explanation

memory leak happens when you forget to call free() for dynamically allocated memory.

How is memory accessed in a dynamically allocated block?

• Using array indexing

• Using pointers

• Both a and b

• Not possible

Answer explanation

You can use either array indexing (ptr[i]) or pointer dereferencing (*(ptr + i)) to access memory.