delete operator in C++ - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the delete operator in C++?

The delete operator frees memory that was previously allocated with new. It helps prevent memory leaks by releasing unused memory back to the system.

beginner

How do you use delete to free a single object allocated with new?

Use delete pointer; where pointer points to the object allocated with new. For example:<br>

int* p = new int(5);
delete p;

beginner

How do you use delete to free an array allocated with new[]?

Use delete[] pointer; to free memory allocated with new[]. For example:<br>

int* arr = new int[10];
delete[] arr;

<br>This ensures all elements are properly destroyed.

intermediate

What happens if you use delete on a pointer that was not allocated with new?

Using delete on memory not allocated by new causes undefined behavior. This can crash the program or corrupt memory. Always delete only what you allocated with new.

intermediate

Why should you set a pointer to nullptr after deleting it?

Setting a pointer to nullptr after deleting prevents accidental use of a dangling pointer, which points to freed memory. This helps avoid bugs and crashes.

Which operator is used to free memory allocated by new in C++?

A remove

B free

C delete

D dispose

The delete operator is used to free memory allocated by new in C++.

How do you correctly delete an array allocated with new[]?

A delete pointer[];

B delete pointer;

C free(pointer);

D delete[] pointer;

Use delete[] pointer; to properly delete arrays allocated with new[].

What is the risk of deleting a pointer twice?

A Undefined behavior and possible crash

B No risk, it's safe

C Memory leak

D Compiler error

Deleting a pointer twice causes undefined behavior and can crash the program.

What should you do after deleting a pointer to avoid dangling pointers?

A Call delete again

B Set it to nullptr

C Do nothing

D Assign it a new value

Setting a pointer to nullptr after deleting prevents accidental use of invalid memory.

What happens if you use delete on a pointer not allocated with new?

A Undefined behavior

B Compiler warning only

C Memory is freed safely

D Nothing happens

Using delete on memory not allocated by new causes undefined behavior.

Explain how and why to use the delete operator in C++.

Think about memory management and avoiding bugs.

What are the risks of incorrect use of the delete operator?

Consider what happens if you delete wrong or forget to delete.