Find limit of recursion: Difference between revisions
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=={{header|REXX}}== |
=={{header|REXX}}== |
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===recursive procedure=== |
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On (IBM's) VM/CMS, the limit of recursion was built-into CMS to stop run-away REXX programs calling recursively, it was either 200 or 250 as I recall. |
On (IBM's) VM/CMS, the limit of recursion was built-into CMS to stop run-away REXX programs calling recursively, it was either 200 or 250 as I recall. |
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<br>This limit was maybe changed later to allow the user to specify the limit. My memory is really fuzzy about these details. |
<br>This limit was maybe changed later to allow the user to specify the limit. My memory is really fuzzy about these details. |
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<lang rexx>/*REXX |
<lang rexx>/*REXX pgm finds the recursion limit: a subroutine that calls itself. */ |
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parse version x; say x; say |
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n=0 |
n=0 |
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call |
call SELF 1 |
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exit /*this statement will never be executed.*/ |
exit /*this statement will never be executed.*/ |
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/*───────────────────────────SELF procedure─────────────────────────────*/ |
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self: procedure expose n |
self: procedure expose n |
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n=n+1 |
n=n+1 |
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if n//100==0 then say n |
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| ⚫ | |||
call self</lang> |
call self</lang> |
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'''output''' using Regina 3. |
'''output''' using Regina 3.6 under Windows/XP Pro |
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<pre style="overflow:scroll"> |
<pre style="overflow:scroll"> |
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REXX-Regina_3.6(MT) 5.00 31 Dec 2011 |
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<br>The recursion level wasn't captured, but the last number shown was 240. |
<br>The recursion level wasn't captured, but the last number shown was 240. |
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<pre style="overflow:scroll"> |
<pre style="overflow:scroll"> |
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REXX/Personal 4.00 21 Mar 1992 |
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10 +++ call self |
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10 +++ call self |
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10 +++ call self |
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10 +++ call self |
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10 +++ call self |
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10 +++ call self |
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10 +++ call self |
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10 +++ call self |
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10 +++ call self |
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4 +++ call |
4 +++ call SELF 1 |
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Error 5 on line |
Error 5 on line 10 of D:\SELF.REX: Machine resources exhausted |
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</pre> |
</pre> |
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'''output''' using R4 REXX under Windows/XP Pro |
'''output''' using R4 REXX under Windows/XP Pro |
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<pre style="overflow:scroll"> |
<pre style="overflow:scroll"> |
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REXX-r4 4.00 29 Apr 2012 |
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<pre> |
<pre> |
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See Category ooRexx for its behavior for this program. |
See Category ooRexx for its behavior for this program. |
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</pre> |
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===resurive subroutine=== |
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<lang rexx>/*REXX pgm finds the recursion limit: a subroutine that calls itself. */ |
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parse version x; say x; say |
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n=0 |
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call SELF 2 |
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exit /*this statement will never be executed.*/ |
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/*───────────────────────────SELF subroutine────────────────────────────*/ |
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self: n=n+1 |
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call self</lang> |
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'''output''' |
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<pre> |
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For Regina 3.6, it was 828,441. |
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For Personnal REXX, it was 240 (the same). |
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For R4, it was 507. |
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</pre> |
</pre> |
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