Runtime evaluation: Difference between revisions

=={{header|REXX}}==

This REXX program does a:

<br> 1) run-time evaluation of an internal expression, and a

<br> 2) run-time evaluation of a user-prompted expression.

<lang rexx>

/*REXX program to illustrate ability to execute code written at runtime.*/

numeric digits 10000000

bee=51

stuff='bee=min(-2,44); say 13*2 "[from inside the box."; abc=abs(bee)'

interpret stuff

say 'bee=' bee

say 'abc=' abc

say

say 'enter an expression:'

pull expression

say

say 'expression entered is:' expression

interpret '?='expression

say

say 'length of result='length(?)

say ' left 50 bytes of result='left(?,50)'...'

say 'right 50 bytes of result=...'right(?,50)

</lang>

Output [with the user entering: <tt> 2**44497 - 1 </tt> ]

<br>which happens to be the 27th Mersenne prime.

<pre style="height:35ex;overflow:scroll">

26 [from inside the box.

bee= -2

abc= 2

enter an expression:

2**44497 - 1

expression entered is: 2**44497 - 1

length of result=13395

left 50 bytes of result=85450982430363380319330070531840303650990159130402...

right 50 bytes of result=...22977396345497637789562340536844867686961011228671

</pre>