Numbers

Pre vs Post Increment

Why does Level++ and ++Level do the same thing? When should I use one over the other?

3D art showing a character using an abacus

While Level++ and ++Level might appear to do the same thing when used alone, they actually behave differently when used within larger expressions. Let's explore the difference:

Basic Behavior

When used in isolation, both increment the variable by 1:

#include <iostream>
using namespace std;

int main() {
  int levelA{5};
  int levelB{5};

  ++levelA; // Pre-increment
  levelB++; // Post-increment

  cout << "levelA: " << levelA << "\n";
  cout << "levelB: " << levelB;
}
levelA: 6
levelB: 6

The Important Difference

The difference becomes apparent when you use them as part of a larger expression:

#include <iostream>

int main() {
  int level{5};

  // Level is incremented, then assigned
  int resultA{++level}; 
  std::cout << "Using ++level:\n";
  std::cout << "level: " << level << "\n";
  std::cout << "resultA: " << resultA << "\n\n";

  level = 5; // Reset level

  // Level is assigned, then incremented
  int resultB{level++}; 
  std::cout << "Using level++:\n";
  std::cout << "level: " << level << "\n";
  std::cout << "resultB: " << resultB;
}
Using ++level:
level: 6
resultA: 6

Using level++:
level: 6
resultB: 5

When to Use Each

Use pre-increment (++level) when:

  • You want the incremented value immediately in the same expression
  • You're writing performance-critical code (pre-increment can be slightly faster)

Use post-increment (level++) when:

  • You need the original value for something before incrementing
  • You're implementing a counter that should increment after its current value is used

Here's a practical example using a game loop:

#include <iostream>
using namespace std;

int main() {
  int turnNumber{1};
  int maxTurns{3};

  while (turnNumber <= maxTurns) {
    cout << "Processing turn " 
      << turnNumber++ << "\n"; 
  }
}
Processing turn 1
Processing turn 2
Processing turn 3

In this example, we use post-increment because we want to display the current turn number before incrementing it for the next iteration.

This Question is from the Lesson:

Numbers

An introduction to the different types of numbers in C++, and how we can do basic math operations on them.

Answers to questions are automatically generated and may not have been reviewed.

This Question is from the Lesson:

Numbers

An introduction to the different types of numbers in C++, and how we can do basic math operations on them.

3D art showing a progammer setting up a development environment
Part of the course:

Intro to C++ Programming

Become a software engineer with C++. Starting from the basics, we guide you step by step along the way

Free, unlimited access

This course includes:

  • 60 Lessons
  • Over 200 Quiz Questions
  • 95% Positive Reviews
  • Regularly Updated
  • Help and FAQ
Free, Unlimited Access

Professional C++

Comprehensive course covering advanced concepts, and how to use them on large-scale projects.

Screenshot from Warhammer: Total War
Screenshot from Tomb Raider
Screenshot from Jedi: Fallen Order
Contact|Privacy Policy|Terms of Use
Copyright © 2024 - All Rights Reserved