Switches

[Steve Andrues]

Is there a way to pass arguments (set switches) to a compiled
program from the comand line, i.e. the /MBR switch to the DOS
Fdisk program, or the /y switch to Xcopy? I know it can be done
in C++ but have not seen any references for this in Power Basic.
Comments? Suggestions?


------------------

[Scott Slater]

You can retrieve the entire command line in PowerBASIC using the
COMMAND$ function.

A$ = COMMAND$
PRINT "The Command Line was : " & A$
END

You can then use functions like INSTR to separate multiple switches.


Scott


------------------

[David Venable]

Here are a couple of functions that make life easier when
dealing with the command line and especially when dealing
with multiple arguments.


' gets the command line and sticks it, separated by spaces,
' into array ar$(). returns the number of elements in the array
'
FUNCTION cmdline( ar$() ) LOCAL PUBLIC

x$ = ltrim$( rtrim$( command$ ) )
a = asplit( x$, ar$() )
function = a

END FUNCTION


' splits string text$ by spaces and puts them into an array
' ar$() and returns the number of elements. Quoted items are
' returned as one item. For example:
' file1 file2 'long file name'
' would return:
' file1
' file2
' 'long file name'

FUNCTION asplit(BYVAL text$, ar$() ) LOCAL PUBLIC

text$=ltrim$(rtrim$(text$))
if text$="" then function=0:exit function
while 1
tlen=len(text$)
cl=instr(text$," ")
za$=left$(text$,1)
if za$=chr$(34) or za$="'" or za$="`" then
z2$=za$
ncl=instr(2, text$, z2$ )
if ncl<>0 then cl=ncl
tp$=ltrim$(rtrim$(left$(text$, cl) ))

else
tp$=ltrim$(rtrim$(left$(text$,cl)))
end if
if cl=0 then tp$=text$:text$=""

incr al
ar$(al)=tp$
text$=ltrim$(rtrim$(right$(text$,tlen-cl)))
if text$="" then exit loop
wend
asplit=al

END FUNCTION




------------------

[Lance Edmonds]

For simple "switches", such as /F, /Q, etc, a simple INSTR() evaluation is usually quite sufficient.

IF INSTR(UCASE$(COMMAND$), "/Q") THEN ' /Q switch present

------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Amos Vryhof]

...or

if TALLY(lcase$(command$), "/q") then '/q switch present...

Amos

------------------
Amos

[Lance Edmonds]

Getting picky here, but in this instance, TALLY() would be slightly less efficient, since it has to parse the entire string. INSTR() would stop as soon as it finds an occurrance.



------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Tom Hanlin]

The speed of parsing the command line is unlikely to be an issue.
Besides, you really ought to be parsing it one character at a time,
so you don't mistake a Unix-style path like /lecture/Question.txt
for a /Q switch!

It might be worth noting that every Microsoft OS since, I think,
DOS 2.0 has supported using "/" delimiters as well as "\" delimiters
for subdirectories. The command shell doesn't always support this
for its own commands, but the OS' interrupts or API calls do. A
first-class program should allow for this possibility. (In which
case, if you expect switches, you should expect that they may be
started off with a hyphen "-" as well as a "/").

------------------
Tom Hanlin
PowerBASIC Staff

[Lance Edmonds]

I did say <U>simple</U> switches...

------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>