Menu
×
   ❮     
HTML CSS JAVASCRIPT SQL PYTHON JAVA PHP HOW TO W3.CSS C C++ C# BOOTSTRAP REACT MYSQL JQUERY EXCEL XML DJANGO NUMPY PANDAS NODEJS DSA TYPESCRIPT ANGULAR ANGULARJS GIT POSTGRESQL MONGODB ASP AI R GO KOTLIN SASS VUE GEN AI SCIPY CYBERSECURITY DATA SCIENCE INTRO TO PROGRAMMING BASH RUST

C++ Tutorial

C++ HOME C++ Intro C++ Get Started C++ Syntax C++ Output C++ Comments C++ Variables C++ User Input C++ Data Types C++ Operators C++ Strings C++ Math C++ Booleans C++ If...Else C++ Switch C++ While Loop C++ For Loop C++ Break/Continue C++ Arrays C++ Structures C++ Enums C++ References C++ Pointers C++ Memory Management

C++ Functions

C++ Functions C++ Function Parameters C++ Function Overloading C++ Scope C++ Recursion C++ Lambda

C++ Classes

C++ OOP C++ Classes/Objects C++ Class Methods C++ Constructors C++ Access Specifiers C++ Encapsulation C++ Friend Functions C++ Inheritance C++ Polymorphism C++ Templates C++ Files C++ Date

C++ Errors

C++ Errors C++ Debugging C++ Exceptions C++ Input Validation

C++ Data Structures

C++ Data Structures & STL C++ Vectors C++ List C++ Stacks C++ Queues C++ Deque C++ Sets C++ Maps C++ Iterators C++ Algorithms

C++ Namespaces

C++ Namespaces

C++ Projects

C++ Projects

C++ How To

C++ Add Two Numbers C++ Random Numbers

C++ Reference

C++ Reference C++ Keywords C++ <iostream> C++ <fstream> C++ <cmath> C++ <string> C++ <cstring> C++ <ctime> C++ <vector> C++ <algorithm>

C++ Examples

C++ Examples C++ Real-Life Examples C++ Compiler C++ Exercises C++ Quiz C++ Syllabus C++ Study Plan C++ Certificate


C++ Booleans


C++ Booleans

Very often, in programming, you will need a data type that can only have one of two values, like:

  • YES / NO
  • ON / OFF
  • TRUE / FALSE

For this, C++ has a bool data type, which can take the values true (1) or false (0).


Boolean Values

A boolean variable is declared with the bool keyword and can take the values true or false:

Example

bool isCodingFun = true;
bool isFishTasty = false;

cout << isCodingFun << "\n";  // Outputs 1 (true)
cout << isFishTasty << "\n"; // Outputs 0 (false)
Try it Yourself »

From the example above, you can read that a true value returns 1, and false returns 0.


Printing true/false With boolalpha

If you prefer to print true and false as words instead of 1 and 0, you can use the boolalpha manipulator:

Example

bool isCodingFun = true;
bool isFishTasty = false;

cout << boolalpha; // enable printing "true"/"false"

cout << isCodingFun << "\n";   // Outputs true
cout << isFishTasty << "\n";  // Outputs false
Try it Yourself »

Note: boolalpha is not a data type. It is an I/O manipulator - a setting that changes how cout displays boolean values. When you use it, you are telling cout: "From now on, print booleans as true and false instead of 1 and 0."


Resetting Back With noboolalpha

If you want to go back to the default behavior (printing 1 and 0), you can use noboolalpha:

Example

bool isCodingFun = true;

cout << boolalpha;   // print as true/false
cout << isCodingFun << "\n";  // Outputs true

cout << noboolalpha; // reset to 1/0
cout << isCodingFun << "\n";  // Outputs 1
Try it Yourself »

Note: It is up to you whether you prefer the default 1 and 0, or the words true and false. Both are correct in C++, and you can switch between them using boolalpha and noboolalpha.

Tip: You can read more about cout and its manipulators in our C++ cout object reference.

In the examples above we used fixed boolean values. But in real programs, boolean values are usually the result of comparing values or variables, which you will learn more about in the next chapter.




×

Contact Sales

If you want to use W3Schools services as an educational institution, team or enterprise, send us an e-mail:
sales@w3schools.com

Report Error

If you want to report an error, or if you want to make a suggestion, send us an e-mail:
help@w3schools.com

W3Schools is optimized for learning and training. Examples might be simplified to improve reading and learning. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. While using W3Schools, you agree to have read and accepted our terms of use, cookie and privacy policy.

Copyright 1999-2025 by Refsnes Data. All Rights Reserved. W3Schools is Powered by W3.CSS.