Memory allocation flow - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is memory allocation in C?

Memory allocation is the process of reserving a portion of computer memory for use by a program. In C, this can be done statically, automatically, or dynamically.

beginner

What function is used to allocate memory dynamically in C?

The malloc() function is used to allocate a block of memory dynamically during program execution.

intermediate

Describe the flow of memory allocation using malloc().

1. Program calls malloc() requesting memory size.<br>2. The system checks for available memory.<br>3. If enough memory is free, it reserves the block.<br>4. malloc() returns a pointer to the start of this block.<br>5. If not enough memory, malloc() returns NULL.

beginner

What should you do after finishing using dynamically allocated memory?

You should free the memory using the free() function to avoid memory leaks and allow the system to reuse that memory.

intermediate

What happens if you forget to free dynamically allocated memory?

The program will have a memory leak, meaning it keeps using more memory over time, which can slow down or crash the system.

Which function in C is used to allocate memory dynamically?

A malloc()

B printf()

C scanf()

D free()

malloc() allocates memory dynamically. free() releases it.

What does malloc() return if it cannot allocate memory?

A A pointer to allocated memory

B An integer 0

C NULL

D A random value

malloc() returns NULL when it fails to allocate memory.

What is the purpose of the free() function?

A Allocate new memory

B Release previously allocated memory

C Check memory size

D Print memory contents

free() releases memory allocated by malloc() or similar functions.

What happens if you use memory after freeing it?

A Undefined behavior, possible crash

B Program runs faster

C Memory is automatically reallocated

D Nothing happens

Using freed memory causes undefined behavior and can crash the program.

Which of these is NOT a type of memory allocation in C?

A Static allocation

B Automatic allocation

C Dynamic allocation

D Virtual allocation

Virtual allocation is not a standard C memory allocation type.

Explain the flow of dynamic memory allocation using malloc() in C.

Think about what happens step-by-step when you ask for memory.

Why is it important to use free() after dynamic memory allocation?

Consider what happens if memory is never released.