declare a boolean in C++

  bool is_boolean_true = true;

This code declares a boolean variable called is_boolean_true, and assigns it a value of true. A boolean is a data type that can be either true or false. In C++, the bool keyword is used to declare a boolean variable. In this case, the variable is_boolean_true has been set to true, meaning the statement is true. This boolean variable can then be used in logic statements and code that require a boolean type. For example, if a program needs to decide whether to execute a certain block of code only when a certain statement is true, a boolean variable like is_boolean_true can be used.