How to resolve the algorithm Short-circuit evaluation step by step in the REXX programming language

Published on 12 May 2024 09:40 PM
#Rexx

How to resolve the algorithm Short-circuit evaluation step by step in the REXX programming language

Table of Contents

Problem Statement

Assume functions   a   and   b   return boolean values,   and further, the execution of function   b   takes considerable resources without side effects, and is to be minimized. If we needed to compute the conjunction   (and): Then it would be best to not compute the value of   b()   if the value of   a()   is computed as   false,   as the value of   x   can then only ever be   false. Similarly, if we needed to compute the disjunction (or): Then it would be best to not compute the value of   b()   if the value of   a()   is computed as   true,   as the value of   y   can then only ever be   true. Some languages will stop further computation of boolean equations as soon as the result is known, so-called   short-circuit evaluation   of boolean expressions

Create two functions named   a   and   b,   that take and return the same boolean value. The functions should also print their name whenever they are called. Calculate and assign the values of the following equations to a variable in such a way that function   b   is only called when necessary: If the language does not have short-circuit evaluation, this might be achieved with nested     if     statements.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Short-circuit evaluation step by step in the REXX programming language

Source code in the rexx programming language

/*REXX programs demonstrates short─circuit evaluation testing  (in an   IF   statement).*/
parse arg LO HI .                                /*obtain optional arguments from the CL*/
if LO=='' | LO==","  then LO= -2                 /*Not specified?  Then use the default.*/
if HI=='' | HI==","  then HI=  2                 /* "      "         "   "   "     "    */

         do j=LO  to HI                          /*process from the  low  to  the  high.*/
         x=a(j)  &  b(j)                         /*compute  function A  and  function B */
         y=a(j)  |  b(j)                         /*   "         "    "   or      "    " */
         if \y  then y=b(j)                      /*   "         "    B   (for negation).*/
         say  copies('═', 30)        '  x=' || x            '  y='y                '  j='j
         say
         end   /*j*/
exit                                             /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
a: say '      A  entered with:'  arg(1);    return abs( arg(1) // 2)   /*1=odd, 0=even  */
b: say '      B  entered with:'  arg(1);    return arg(1) < 0          /*1=neg, 0=if not*/

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