Robert Wallick: FileSize more global in scope, ⎕ELX resets to entrant value

2015-01-26T16:54:10Z

FileSize more global in scope, ⎕ELX resets to entrant value

← Older revision		Revision as of 12:54, 26 January 2015
Line 7:		Line 7:
	!style="background:lightgrey; padding:12px;" align="left"\|		!style="background:lightgrey; padding:12px;" align="left"\|

	lNumBytes←FileSize strFileName;iTieNum;iRet <br>		lNumBytes←FileSize strFileName;iTieNum;iRet;strELXwas <br>
	⍝Returns file size in bytes. If file does not exist, returns -1 <br>		⍝Returns file size in bytes. If file does not exist, returns -1 <br>
	⍝Sample call: FileSize "C:/FileName.txt" <br>		⍝Sample call: FileSize "C:/FileName.txt" <br>
			strELXwas←⎕ELX <br>
	⎕ELX←"→ErrFileSiz" ⍝On error(e.g. file not found), goto ErrFileSiz line <br>		⎕ELX←"→ErrFileSiz" ⍝On error(e.g. file not found), goto ErrFileSiz line <br>
	iTieNum←strFileName ⎕NTIE 0 ⍝Open file as if for reading, obtain tie number <br>		iTieNum←strFileName ⎕NTIE 0 ⍝Open file as if for reading, obtain tie number <br>
	lNumBytes←⎕NSIZE iTieNum ⍝Read in file size, normal operation, file found <br>		lNumBytes←⎕NSIZE iTieNum ⍝Read in file size, normal operation, file found <br>
	iRet←⎕NUNTIE iTieNum ⍝Finished with file read, close/untie file # <br>		iRet←⎕NUNTIE iTieNum ⍝Finished with file read, close/untie file # <br>
	~~⎕ELX←"⎕DM"~~ ⍝Reset error execute function - to its default value <br>		⎕ELX←strELXwas ⍝Reset error execute function - to its entrant value. Note default initial value: ⎕ELX←"⎕DM" <br>
	→0 <br>		→0 <br>
	ErrFileSiz: lNumBytes←-1 ⍝On error, program branches here; sets # bytes found to -1 <br>		ErrFileSiz: lNumBytes←-1 ⍝On error, program branches here; sets # bytes found to -1 <br>
	~~⎕ELX←"⎕DM"~~ ⍝Reset error execute function - to its default value <br>		⎕ELX←strELXwas ⍝Reset error execute function - to its entrant value. Note default initial value: ⎕ELX←"⎕DM" <br>
	→0		→0 <br>
	\|-		\|-
	\|}		\|}
			APL concepts demonstrated: '''Branching, Commenting, Exiting a Function, System Functions, use of Local Variables, Error Trapping'''.
	<hr align="center" color="gray" size="2" width="80%">		<hr align="center" color="gray" size="2" width="80%">
	<br>		<br>
	See Also: [[System_Function_NNAMES#.E2.8E.95NNAMES\|System Functions - Quad NNames]], [[System_Variable_ELX\|Quad ELX]]		See Also: [[System_Function_NNAMES#.E2.8E.95NNAMES\|System Functions - Quad NNames]], [[System_Variable_ELX\|Quad ELX]]

Robert Wallick: Examples - Working with Files

2015-01-26T02:00:30Z

Examples - Working with Files

New page

:{goto} [[Examples]] - Go back to examples

<hr align="center" color="gray" size="2" width="45%">
''Example 1 - NARS2000 User APL Function'': '''FileSize'''     Uses System Functions/Variables: '''⎕NTIE ⎕NSIZE ⎕NUNTIE ⎕ELX''' 

{| class=sortable border="0"
!style="background:lightgrey; padding:12px;" align="left"|

lNumBytes←FileSize strFileName;iTieNum;iRet 
⍝Returns file size in bytes. If file does not exist, returns -1 
⍝Sample call: FileSize "C:/FileName.txt" 
⎕ELX←"→ErrFileSiz" ⍝On error(e.g. file not found), goto ErrFileSiz line 
iTieNum←strFileName ⎕NTIE 0 ⍝Open file as if for reading, obtain tie number 
lNumBytes←⎕NSIZE iTieNum ⍝Read in file size, normal operation, file found 
iRet←⎕NUNTIE iTieNum ⍝Finished with file read, close/untie file # 
⎕ELX←"⎕DM" ⍝Reset error execute function - to its default value 
→0 
ErrFileSiz: lNumBytes←-1 ⍝On error, program branches here; sets # bytes found to -1 
⎕ELX←"⎕DM" ⍝Reset error execute function - to its default value 
→0
|-
|}

<hr align="center" color="gray" size="2" width="80%">
 
See Also: [[System_Function_NNAMES#.E2.8E.95NNAMES|System Functions - Quad NNames]], [[System_Variable_ELX|Quad ELX]]

Examples/Files - Revision history

Robert Wallick: FileSize more global in scope, ⎕ELX resets to entrant value

Robert Wallick: Examples - Working with Files