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Re: the last line of a large file [message #55242 is a reply to message #55238]

Thu, 09 August 2007 14:22

Paul Van Delst[1]
Messages: 1157
Registered: April 2002

Senior Member

Jean H. wrote:
> Hi,
>
> If you are sure it is the last line that you want to omit, you could do
> something like:
>
> nbOfLines = FILE_LINES(YourFileName)
>
> for i = 0, nbOfLines - 2 do begin
> readf, in_unit, input_line
> endfor

Or, if each record is the same format and consists only of numbers (no A-Z characters),
you could probably get rid of the above loop too. E.g. say you have 10 columns of numbers
per record (line)

n_Records = FILE_LINES(YourFileName) - 1L
...open the file....
All_the_Useful_Data = FLTARR(10,n_Records)
readf, in_unit, All_the_Useful_Data

?

I think that should work (or something like it).

Of course, if you have records split over multiple lines, then it gets hairier.

>>
>> I am processing a large file with data in the same format till the
>> last line. In the last line, it states how many records are included
>> in this file.
>>
>> So the structure of my program is:
>>
>> while not eof(in_unit) do begin
>> readf, in_unit, input_line
>> if( input_line ne 'last line) then begin
>> .....
>> else
>> ....
>> endif
>> endwhile
>>
>> Do I have to use 'if/then' to test whether every input_line is the
>> last line of the file? Since there are many data records in the file,
>> repeat calls to 'if/then' can be time consuming. But if I don't do the
>> test, the program will be halted when it read in the last line.
>>
>> A Easy way I can think of is to delete the last line, but sometime we
>> are not supposed to change the input files.

You should also tell the people who wrote the code that creates the files that the number
of records information is more useful if they stick it at the beginning of the file. :o)

cheers,

paulv

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[Message index]

		Re: the last line of a large file By: queiny on Fri, 10 August 2007 07:00
		Re: the last line of a large file By: Conor on Fri, 10 August 2007 05:34
		Re: the last line of a large file By: Paul Van Delst[1] on Thu, 09 August 2007 14:22
		Re: the last line of a large file By: Jean H. on Thu, 09 August 2007 13:07
		Re: the last line of a large file By: Carsten Lechte on Fri, 10 August 2007 08:00
		Re: the last line of a large file By: David Fanning on Fri, 10 August 2007 07:10
		Re: the last line of a large file By: Paul Van Delst[1] on Fri, 10 August 2007 07:37

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