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0.9b (c) 1995 Peter Childs
Some features of REXX that you can use to write more intricate procedures will be discussed in this section. You will see how to have a procedure make decisions by testing a value with the IF instruction. You will also see how to compare values and determine if an expression is true or false. A brief description of the terms covered in this section follows below:
IF Used with THEN. Checks if the expression
is true. Makes a decision about a single
instruction.
THEN Identifies the instruction to be run if the
expression is true.
ELSE Identifies the instruction to be run if the
expression is false.
SELECT Tells the interpreter to select one of a
number of instructions.
WHEN Used with SELECT. Identifies an expression
to be tested.
OTHERWISE Used with SELECT. Indicates the
instruction to be run if expressions tested
are false.
DO-END Indicates that a group of instructions
should be run.
NOP Indicates that nothing is to happen for one
expression.
Comparisons > < = Indicates greater than, less than, equal
to.
NOT Operator ¬ or \ Changes the value of a term from true to
false, or from false to true.
AND Operator & Gives the value of true if both terms are
true.
OR Operator | Gives the value of true unless both terms
are false.
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