Why dynamic memory is needed in C++ - Quick Recap

Recall & Review

beginner

What is dynamic memory in C++?

Dynamic memory is memory allocated during program execution (runtime) using operators like new and delete. It allows flexible use of memory based on program needs.

beginner

Why can't we always use static memory allocation?

Static memory is fixed at compile time and can't change size during program run. Dynamic memory is needed when the amount of data is unknown or changes while the program runs.

beginner

How does dynamic memory help with variable data sizes?

Dynamic memory lets programs allocate exactly the amount of memory needed at runtime, like when reading user input or loading files of unknown size.

beginner

What is a real-life example of needing dynamic memory?

Imagine packing a suitcase without knowing how many clothes you'll bring. Dynamic memory is like having a suitcase that can grow or shrink as you add or remove clothes.

intermediate

What happens if you don't free dynamic memory?

If you don't free dynamic memory with delete, your program can waste memory (memory leak), which may slow down or crash the program over time.

Why do we use dynamic memory in C++?

A To allocate memory during program execution based on need

B To allocate memory only at compile time

C To make programs run faster by avoiding memory allocation

D To store constants only

Dynamic memory allows programs to allocate memory while running, adapting to changing data sizes.

Which operator is used to allocate dynamic memory in C++?

A new

B malloc

C alloc

D create

The new operator allocates dynamic memory in C++.

What is a risk of not freeing dynamic memory?

A Faster program execution

B Memory leak causing wasted memory

C Program will automatically free memory

D No effect on program

Not freeing dynamic memory causes memory leaks, which waste memory and can crash programs.

When is dynamic memory especially useful?

A When data size is fixed and known

B When program runs only once

C When data size is unknown or changes during runtime

D When program uses only constants

Dynamic memory is useful when data size is unknown or changes while the program runs.

Which of these is NOT a feature of dynamic memory?

A Must be manually freed

B Allocated at runtime

C Can be resized by allocating new memory

D Fixed size at compile time

Dynamic memory is NOT fixed size at compile time; that describes static memory.

Explain why dynamic memory is needed in C++ programs.

Think about programs that don't know how much data they will handle before running.

Describe what can happen if dynamic memory is not properly managed.

Consider what happens if you keep taking memory but never give it back.