Statements and expressions

The specification of an action is called a statement. Statements can be interpreted (executed), and that interpretation (execution) has an effect. The effect is a transformation of the state of the computation, the state being represented by the collective values of the program’s variables. The most elementary action is the assignment of a value to a variable. The assignment statement has the form$ assignment = designator “: =” expression.and its corresponding action consists of three parts in this sequence: 1.evaluate the designator designating a variable,2.evaluate the expression yielding a value,3.replace the value of the variable identified in 1. by the value obtained in 2.