bool (C++)

This keyword is a built-in type. A variable of this type can have values true and false. Conditional expressions have the type bool and so have values of type bool. For example, i!=0 now has TRUE or FALSE depending on the value of i.

Visual Studio 2017 version 15.3 and later (available with /std:c++17): The operand of a postfix or prefix increment or decrement operator may not be of type bool. In other words, given a variable b of type bool, these expressions are no longer allowed:


The values TRUE and FALSE have the following relationship:

!false == true
!true == false

In the following statement:

if (condexpr1) statement1;

If condexpr1 is TRUE, statement1 is always executed; if condexpr1 is FALSE, statement1 is never executed.

When a postfix or prefix ++ operator is applied to a variable of type bool, the variable is set to TRUE. Visual Studio 2017 version 15.3 and later: operator++ for bool was removed from the language and is no longer supported.

The postfix or prefix -- operator cannot be applied to a variable of this type.

The bool type participates in integral promotions. An r-value of type bool can be converted to an r-value of type int, with FALSE becoming zero and TRUE becoming one. As a distinct type, bool participates in overload resolution.

See also

Fundamental Types