The C++Course provides a general introduction to programming in C++. It is based on A.B. Downey's book, How to Think Like a Computer Scientist. Click here for details.

Boolean Values

The types we have seen so far are pretty big. There are a lot of integers in the world, and even more floating-point numbers. By comparison, the set of characters is pretty small. Well, there is another type in C++ that is even smaller. It is called boolean, and the only values in it are true and false.

Without thinking about it, we have been using boolean values for the last couple of chapters. The condition inside an if statement or a while statement is a boolean expression. Also, the result of a comparison operator is a boolean value. For example:

  if (x == 5) {
    // do something

The operator == compares two integers and produces a boolean value.

The values true and false are keywords in C++, and can be used anywhere a boolean expression is called for. For example,

  while (true) {
    // loop forever

is a standard idiom for a loop that should run forever (or until it reaches a return or break statement).

Last Update: 2005-12-05