 Let's wrap up our discussion of C data types with two other types that are quite useful. Character and Boolean. Variables with a char or character data type. Take up one byte and contain exactly one character. The character must be enclosed in single quote marks. Because character variables are one byte, you can't assign multi-character Unicode constants to char variables. These, however, are valid. The backslash is the escape character. It says to treat the following character as special. The first example says that instead of a regular letter N, interpret this as a new line character. The second example says that instead of a regular letter T, treat it as a tab character. The next question. How would you put an apostrophe or a backslash character into a variable? The answer is, use backslash again. It will escape these special characters until C to treat them as if they were ordinary characters. That's what the backslash escape character does. It makes ordinary characters special, and it makes special characters ordinary. To print a character variable, use the %C format specifier. Our last data type is the Boolean data type, underscore bool. The name starts with an underscore because it's a system-level entity, and the B is capitalized because that is the convention for declaring data types, as opposed to ordinary variables. The Boolean data type is named after George Boole, an English mathematician who wrote about the rules of logic, using an algebra where your only values are true and false rather than numbers. When you assign values to a Boolean variable, which takes up one byte, use 0 for false and 1 is true. In fact, any non-zero value is considered to be true and will be translated to 1 when stored in the variable, but this is considered to be very bad programming style. Instead, stick to 0 for false and 1 for true. To print a Boolean variable, use %I. Most of the time, you'll use Boolean variables in if statements, which we will get to in a couple of chapters.