Assignment Statements

An assignment statement assigns a value to a storage location. For example, the following statement assigns the integer 25 to the location represented by the variable carrots:

carrots = 25;

The = symbol is called the assignment operator. One unusual feature of C++ (and C) is that you can use the assignment operator serially. For example, the following is valid code:

int steinway;
int baldwin;
int yamaha;
yamaha = baldwin = steinway = 88;

The assignment works from right to left. First, 88 is assigned to steinway; then the value of steinway, which is now 88, is assigned to baldwin; then baldwin’s value of 88 is assigned to yamaha. (C++ follows C’s penchant for allowing weird-appearing code.)

The second assignment statement in Listing 2.2 demonstrates that you can change the value of a variable:

carrots = carrots - 1;  // modify the variable

The expression to the right of the assignment operator (carrots – 1) is an example of an arithmetic expression. The computer will subtract 1 from 25, the value of carrots, obtaining 24. The assignment operator then stores this new value in the carrots location.