| Re: Read Total lines in an ASCII file [message #33397 is a reply to message #33175] |
Fri, 20 December 2002 18:41  |
Jeff Guerber
Messages: 41
Registered: July 2000
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Member |
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On 20 Dec 2002, Big Bird wrote:
> As far as I recall, the OP just wanted to know the number of lines,
> not necessarily try to convert them into anything. The only deviation
> from the usual 10b linefeed out there on idl'ish platforms is the DOS
> [10b,13b] LF/CR, right? Or do VMS systems do yet something different?
> How do the various suggested methods hold up on VMS?
I haven't used VMS in a number of years (thank goodness!), but IIRC it
had about 5 or 6 different file types, most of which could be used for
ASCII files... Ahh, here's my old copy of "Programming in VAX Fortran"
(1984 ed; I kept it because it makes a pretty good Fortran 77 reference):
the RECORDTYPE keyword to OPEN had 6 possible values (fixed, variable,
segmented, stream, stream_cr, stream_lf). As I recall, "variable", which
started each record with a 2-byte (4-byte?) length count, was pretty
common for text files, even more than the "stream" types. Then there was
ORGANIZATION which could be sequential, relative, or indexed...
And I think I read somewhere that Macs use (used?) just CR.
> If the LF and CR/LF are the only two, the only thing you'd have to do
> is counting the number of 10b in the byte-filed:
>
> f = read_binary('Big_honking_example_file')
> h = histogram(f)
> print,h[10]
> 1479054
>
> If you're really intent on accessing the individual data items in the
> file, you could retain the reverse indices of the histogram for a
> handy field of pointers to each individual line that can be converted
> into a string at will...
That's pretty cool, but wouldn't they point to the _ends_ of the lines?
I suppose you could add 1, pop off the last value, and push a 0 onto the
front of the array.
Jeff Guerber
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