Increment and decrement operators in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of mixed pre and post increment

What is the output of this C++ code snippet?

C++

int x = 5;
int y = x++ + ++x;
std::cout << y << std::endl;

A 13

B 11

C 10

D 12

💡 Hint

Remember that post-increment returns the value before incrementing, pre-increment increments first.

x++ returns 5 then x becomes 6; ++x increments x to 7 then returns 7; sum is 5 + 7 = 12.

❓ Predict Output

intermediate

Effect of multiple increments in one expression

What is the output of this C++ code?

C++

int a = 3;
int b = ++a + a++ + ++a;
std::cout << b << std::endl;

A 14

B 15

C 12

D 13

💡 Hint

Evaluate increments from left to right, updating 'a' after each operation.

++a increments a to 4 and returns 4; a++ returns 4 then increments a to 5; ++a increments a to 6 and returns 6; sum = 4 + 4 + 6 = 14.

❓ Predict Output

advanced

Output with decrement operators in complex expression

What is the output of this C++ code?

C++

int i = 4;
int j = i-- - --i + i--;
std::cout << j << std::endl;

A 4

B 3

C 2

D 5

💡 Hint

Remember post-decrement returns value before decrement, pre-decrement decrements first.

i-- returns 4 then i=3; --i decrements i to 2 returns 2; i-- returns 2 then i=1; sum = 4 - 2 + 2 = 4.

❓ Predict Output

advanced

Value of variable after increments and decrements

What is the value of 'x' after running this code?

C++

int x = 10;
x = ++x + x++ - --x + x--;
std::cout << x << std::endl;

A 20

B 22

C 19

D 21

💡 Hint

Track the value of x carefully after each increment or decrement.

Stepwise: ++x increments x to 11 returns 11; x++ returns 11 then x=12; --x decrements x to 11 returns 11; x-- returns 11 then x=10; sum=11+11-11+11=22; x assigned 22.

❓ Predict Output

expert

Output of complex expression with increments and decrements

What is the output of this C++ code snippet?

C++

int n = 5;
int result = n++ + ++n - --n + n-- + n;
std::cout << result << std::endl;

A 27

B 28

C 17

D 30

💡 Hint

Evaluate each increment/decrement carefully and update 'n' after each operation.

n++ returns 5 (n=6); ++n increments n to 7 returns 7; --n decrements n to 6 returns 6; n-- returns 6 (n=5); n=5; sum=5+7-6+6+5=17.