C++ How to Program, 10/e

4.12 Compound Assignment Operators

The compound assignment operators abbreviate assignment expressions. Statements like

variable = variable  operator  expression;

where operator is one of the binary operators +, -, *, / or % (or others we discuss later in the text) can be written in the form

variable  operator=  expression;

For example, you can abbreviate the statement

c = c + 3;

with the addition compound assignment operator, +=, as

c += 3;

The += operator adds the value of the expression on its right to the value of the variable on its left and stores the result in the variable on the left of the operator. Thus, the assignment expression c += 3 adds 3 to c. Figure 4.15 shows the arithmetic compound assignment operators, sample expressions ...