C++ Boolean Data Type

In C++, a Boolean data type is a data type that can have only two possible values, true and false. It is a built-in data type, defined in the cstdbool header file. The Boolean data type is used to represent logical values, such as true or false, on or off, yes or no, etc. It is typically used in conditional statements and loops to control the flow of a program.

Declaring Boolean Variables

In C++, Boolean variables are declared using the bool keyword. They can be assigned either true or false values. Here is an example of how to declare and initialize a Boolean variable:

#include <iostream>
using namespace std;
int main() {
    bool isTrue = true;
    cout << "Value of isTrue: " << isTrue << endl;
    return 0;

In this example, we have declared a Boolean variable named isTrue and initialized it with the value true. The cout statement prints the value of isTrue which is 1 for true and 0 for false.

Boolean Expressions

A Boolean expression is an expression that evaluates to either true or false. C++ provides several comparison operators that can be used to create Boolean expressions. Here is a list of comparison operators in C++:

  • ==: Equal to
  • !=: Not equal to
  • >: Greater than
  • >=: Greater than or equal to
  • <: Less than
  • <=: Less than or equal to

Here is an example of a Boolean expression that uses a comparison operator:

#include <iostream>
using namespace std;
int main() {
    int x = 5;
    int y = 10;
    bool isGreater = x > y;
    cout << "is x greater than y: " << isGreater << endl;
    return 0;

In this example, we have created a Boolean expression x > y that compares the values of two integer variables x and y. The expression will evaluate to false as 5 is not greater than 10. The output will be is x greater than y: 0.

Boolean Logical Operators

C++ also provides several logical operators that can be used with Boolean variables or expressions. These include:

  • && (and): Returns true if both operands are true.
  • || (or): Returns true if either operand is true.
  • ! (not): Inverts the value of the operand, i.e. if the operand is true, it returns false and vice versa.
#include <iostream>
using namespace std;
int main() {
    bool a = true;
    bool b = false;
    cout << "a && b: " << (a && b) << endl;
    cout << "a || b: " << (a || b) << endl;
    cout << "!a: " << (!a) << endl;

In this example, the first output is false because both a and b are not true, the second output is true because at least one of a and b is true, and the third output is false because the value of a is inverted.


Boolean data type in C++ is used to represent true or false values. It is a very important data type in decision-making and logical operations. In this article, we have discussed the basic use of Boolean data type, how to define and initialize Boolean variables and how to use them with logical operators. Understanding the basics of Boolean data type is crucial for any programmer as it is used in almost every program.

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