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Operator
Meaning
& AND
Returns 1 if both comparisons are true. For example:
(4 > 2) & (a = a) /* true, so result is 1 */
(2 > 4) & (a = a) /* false, so result is 0 */
| Inclusive OR
Returns 1 if at least one comparison is true. For example:
(4 > 2) | (5 = 3) /* at least one is true, so result is 1 */
(2 > 4) | (5 = 3) /* neither one is true, so result is 0 */
&& Exclusive OR
Returns 1 if only one comparison (but not both) is true. For example:
(4 > 2) && (5 = 3) /* only one is true, so result is 1 */
(4 > 2) && (5 = 5) /* both are true, so result is 0 */
(2 > 4) && (5 = 3) /* neither one is true, so result is 0 */
Prefix \,¬
Logical NOT
Negates—returning the opposite response. For example:
\ 0 /* opposite of 0, so result is 1 */
\ (4 > 2) /* opposite of true, so result is 0 */
Using Logical Expressions
You can use logical expressions in complex conditional instructions and as checkpoints to screen
unwanted conditions. When you have a series of logical expressions, for clarification, use one or more
sets of parentheses to enclose each expression.
IF ((A < B) | (J < D)) & ((M = Q) | (M = D)) THEN ....
The following example uses logical operators to make a decision.
When arguments passed to this example are SPRING YES NO, the IF clause translates as follows:
IF ((season = 'WINTER') | (snowing ='YES')) & (broken_leg ='NO') THEN
\______________/ \____________/ \_____________/
false true true
/****************************** REXX ********************************/
/* This program receives arguments for a complex logical expression */
/* that determines whether a person should go skiing. The first */
/* argument is a season and the other two can be 'yes' or 'no'. */
/********************************************************************/
PARSE ARG season snowing broken_leg
IF ((season = 'WINTER') | (snowing ='YES')) & (broken_leg ='NO')
THEN SAY 'Go skiing.'
ELSE
SAY 'Stay home.'
Figure 13. Example Using Logical Expressions
Using Variables and Expressions
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CICS TS for VSE/ESA: REXX Guide