| static variable mayhem [message #11685] |
Mon, 11 May 1998 00:00  |
T Bowers
Messages: 56
Registered: May 1998
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Member |
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Hi.
I'm trying to do something very simple, but IDL 5.02 is fighting me. I'm
trying
to have what would be a static variable in c/c++ in a function set as a flag
so
that it is initialized when i come in, like so:
function foofunc, x
;In c/c++ I would put this next line to init my flag the 1st time this fn
is called
; from foopro below.
;static int firstTimeInFooFunc = 1; ;Set to 1 ONLY the 1st time foofunc
called
if (firstTimeInFooFunc) then begin
firstTimeInFooFunc = 0 ;Set so this'll never happen again on subsequent
calls
return, x = x - 1
endif $
else return, x = x + 1
end
pro foopro
x = foofunc(0)
print, x
x = foofunc(x)
print, x
x = foofunc(x)
print, x
return
end
the output I want is:
-1
0
1
I tried:
function foofunc, x
common CBlock, firstTimeInFooFunc = 1
...
but IDL won't let me initialize firstTimeInFooFunc like this.
Then I thought probably IDL would initialize it for me automatically to 0.
So i just changed the code to:
...
function foofunc, x
common CBlock, firstTimeInFooFunc ;I think this'll init to 0
if (NOT firstTimeInFooFunc) then begin ;init'd to 0, so I'll just NOT
the bastard
firstTimeInFooFunc = 1 ;Set so this'll never happen again on subsequent
calls
return, x = x - 1
endif $
...
No such luck. It compiles, but when I single step to this line, I get
% Variable is undefined: FIRSTTIMEINFOOFUNC (CBLOCK).
% Execution halted at: FOOFUNC blah, blah, blah
I'm *sure* I'm missing something here. Doesn't IDL have static variables?
Can anybody help, please?
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