Example Using A Comparison Expression
/****************************** REXX *******************************/
/* This exec compares what you paid for lunch for two */
/* days in a row and then comments on the comparison. */
/*******************************************************************/
SAY 'What did you spend for lunch yesterday?'
SAY 'Please do not include the dollar sign.'
PARSE PULL last
SAY 'What did you spend for lunch today?'
SAY 'Please do not include the dollar sign.'
PARSE PULL lunch
IF lunch > last THEN /* lunch cost increased */
SAY "Today's lunch cost more than yesterday's."
ELSE /* lunch cost remained the same or decreased */
SAY "Today's lunch cost the same or less than yesterday's."
Exercises - Using Comparison Expressions
1. In the preceding example of using a comparison expression, what appears on
the screen when you respond to the prompts with the following lunch costs?
Yesterday’s Lunch Today’s Lunch
4.42 3.75
3.50 3.50
3.75 4.42
2. What is the result (0 or 1) of the following expressions?
a. ″Apples″ = ″Oranges″
b. ″ Apples″ = ″Apples″
c. ″ Apples″ == ″Apples″
d. 100 = 1E2
e. 100 \= 1E2
f. 100 \== 1E2
ANSWERS
1. The following sentences appear.
a. Today’s lunch cost the same or less than yesterday’s.
b. Today’s lunch cost the same or less than yesterday’s.
c. Today’s lunch cost more than yesterday’s.
2. The expressions result in the following. Remember 0 is false and 1 is true.
a. 0
b. 1
c. 0 (The first ″ Apples″ has a space.)
d. 1
e. 0
f. 1
Logical (Boolean) Operators
Logical expressions, like comparison expressions, return a true (1) or false (0) value
when processed. Logical operators combine two comparisons and return the true
(1) or false (0) value depending on the results of the comparisons.
Using Expressions
32
z/OS V1R1.0 TSO/E REXX User’s Guide
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