5 Control Statements

Statements normally execute in the order in which they are written. However, you can alter the normal order of execution by transferring control to another section of a program unit or a subprogram. Transfer of control can be conditional or unconditional. Conditional transfer occurs only when specified conditions are met at a certain point in a program unit. Unconditional transfer occurs each time a certain point is reached in a program unit.

A control statement (or construct) transfers control to a point within the same program unit or to another program unit. Such a statement governs iterative processing, suspension of program execution, and program termination.

On Alpha processors, a control construct (CASE, DO, and IF) can be given a symbolic name. The name must be a unique identifier in the program unit, and must appear on the initial line and terminal line of the construct. On the initial line, the name is separated from the statement keyword by a colon (:), for example, [name:]SELECT CASE.

The following are control statements or constructs:


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