Increment and decrement operators in C++ - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the increment operator (++) do in C++?

The increment operator (++) increases the value of a variable by 1.

intermediate

Explain the difference between prefix (++x) and postfix (x++) increment operators.

Prefix (++x) increases the value first, then uses it. Postfix (x++) uses the current value first, then increases it.

beginner

What does the decrement operator (--) do in C++?

The decrement operator (--) decreases the value of a variable by 1.

intermediate

How does the postfix decrement operator (x--) behave in an expression?

It uses the current value of x in the expression, then decreases x by 1 after.

advanced

Can increment and decrement operators be used with non-integer types like floats or pointers?

Yes. Increment and decrement operators can be used with floats (increase/decrease by 1.0) and pointers (move to next/previous memory address).

What is the value of x after this code? int x = 5; int y = ++x;

A x = 5, y = 6

B x = 6, y = 6

C x = 6, y = 5

D x = 5, y = 5

Prefix ++x increases x first to 6, then assigns y = 6.

What is the value of y after this code? int x = 5; int y = x++;

A y = 6

B y = 4

C y = 7

D y = 5

Postfix x++ uses x's current value (5) for y, then increments x.

Which operator decreases a variable's value by 1?

A --

B ++

C +=

D -=

The decrement operator (--) decreases the value by 1.

If int x = 10; what is the value of x after x--?

A 9

B 10

C 11

D Undefined

x-- decreases x by 1, so x becomes 9.

Can you use ++ operator on a pointer variable?

A No, ++ only works on integers.

B Yes, but it resets the pointer to null.

C Yes, it moves the pointer to the next memory location.

D No, pointers cannot be changed.

Incrementing a pointer moves it to the next element in memory.

Describe how prefix and postfix increment operators differ in behavior.

Think about when the variable changes relative to its use.

Explain how decrement operators work and give an example with both prefix and postfix forms.

Compare with increment operators but in reverse.