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Re: unformatted strings (reading) [message #5719 is a reply to message #5718]

Sat, 03 February 1996 00:00

Jackel
Messages: 30
Registered: April 1993

Member

In article <4eule1$si1@news.alaska.edu> immel@gi.alaska.edu (Thomas Immel) writes:
> Here's a question for anyone who reads unformatted strings.
> Is there a way to read a whole ,say 10 character, string at once
> in IDL?

Not in general. When written as standard binary, strings don't contain any
information about their length, or markers between them. Consequently, IDL
has no way of knowing how many bytes to read. However, in the XDR binary
mode, stringlengths are stored along with the string, allowing something like
the following:

IDL> teststrings= ['This','is','a','set of','test strings. Okay?']
IDL> openw,1,'test.dat',/XDR
IDL> writeu,1,teststrings
IDL> close,1

IDL> openr,1,'test.dat',/XDR
IDL> newstrings= strarr(5) ;define some strings, don't worry about their lengths
IDL> readu,1,newstrings
IDL> print,newstrings
This is a set of test strings. Okay?

Of course, this is only useful if you can make sure XDR is used in the first
place (and if you had control over the writing you could just pad everything
out to some known length). Otherwise you can try things like searching for
spaces (like another poster suggested), but that could get messy if there are
non-strings mixed in with the data. Good luck.

Brian Jackel
University of Western Ontario

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[Message index]

		Re: unformatted strings (reading) By: David Foster on Wed, 07 February 1996 00:00
		Re: unformatted strings (reading) By: immel on Sun, 04 February 1996 00:00
		Re: unformatted strings (reading) By: Jackel on Sat, 03 February 1996 00:00
		Re: unformatted strings (reading) By: agraps on Sat, 03 February 1996 00:00

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