Sams Teach Yourself C++ in 24 Hours, Third Edition

Expressions

Any statement that returns a value is an expression in C++.

There it is, plain and simple. If it returns a value, it is an expression. All expressions are statements.

The myriad pieces of code that qualify as an expression might surprise you. Here are three examples:

3.2                       // returns the value 3.2
PI                        // float const that returns the value 3.14
SecondsPerMinute          // int const that returns 60

Assuming that PI is a const equal to 3.14 and SecondsPerMinute is a constant equal to 60, all three of these statements are expressions.

The complicated expression

x = a + b;

not only adds a and b and assigns the result to x, but yields the value ...