Re: writeu, printf, readu/f 2 file

[Craig Markwardt <craigmnet(at)cow.physics.wisc.edu>]

Without delving into too much detail about your specific program, I
can say that you should pay a lot more attention to your output
formatting.  Don't assume, simply because you print it out one way, it
can be read the same way.  For example:

IDL> openw, 50, 'test.dat'
IDL> printf, 50, 1, '2 3', 4     
IDL> close, 50              
IDL> openr, 50, 'test.dat'
IDL> a = 0 & b = '' & c = 0
IDL> readf, 50, a, b, c
% READF: End of file encountered. Unit: 50
         File: test.dat
% Execution halted at:  $MAIN$                 

Hmmm, why did this fail?  Well, the string B is very greedy and it
consumes everything to the end of the line, including the "4".

Mixing formatted and unformatted data in a file can be tricky.  The
problem is that when you read formatted data the file pointer can
advance unpredictably.  Better to read and write the data
intermediately to a string buffer.

Craig


"Sean Heukels" <sean77=cuthere=@dds.nl> writes:

> Can writeu, and printf be combined ?? in one write action.
> Or is it the one or the other ?
> I've been trying everything. The whole day and it still doesn't work.
> 
> What I want to do is write some txt and variables, that define
> the following data block and ofcourse the time and location, etc
> In the header. But somehow, the firt line reads fine, but after that
> everything is garbled.
> I think it has something to do with the different write/read statements
> 
> See sample code that is not working
... deleted ...

-- 
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Craig B. Markwardt, Ph.D.         EMAIL:    craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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