THE WORLD'S LARGEST WEB DEVELOPER SITE

# 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 only take the values `true` or `false`:

### Example

bool isCodingFun = true;
bool isFishTasty = false;
cout << isCodingFun;  // Outputs 1 (true)
cout << isFishTasty;  // Outputs 0 (false)
Run example »

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

However, it is more common to return boolean values from boolean expressions (see below).

## Boolean Expression

A Boolean expression is a C++ expression that returns a boolean value: `1` (true) or `0` (false).

You can use a comparison operator, such as the greater than (`>`) operator to find out if an expression (or a variable) is true:

### Example

int x = 10;
int y = 9;
cout << (x > y); // returns 1 (true), because 10 is higher than 9
Run example »

Or even easier:

### Example

cout << (10 > 9); // returns 1 (true), because 10 is higher than 9
Run example »

In the examples below, we use the equal to (`==`) operator to evaluate an expression:

### Example

int x = 10;
cout << (x == 10);  // returns 1 (true), because the value of x is equal to 10
Run example »

### Example

cout << (10 == 15);  // returns 0 (false), because 10 is not equal to 15
Run example »

Booleans are the basis for all C++ comparisons and conditions.

## Exercise:

Fill in the missing parts to print the values `1` (for true) and `0` (for false):

``` isCodingFun = true;
isFishTasty = false;
cout << ;
cout << ;
```

Start the Exercise