Re: How to Read Files? [was: Re: learning perl 3rd vs 4th]

Hello

The spec does not allow for carriage returns or line feeds making it 
a long line. Is there a way to read "x" number of bytes?

Andrew

At 11:10 AM 5/25/2008, Rob Dixon wrote:
>Hi Andrew
>
>(If you are asking a new question of this group please make a fresh 
>post with an
>appropriate subject line rather than replying to the end of an old 
>thread. Many
>of us have email clients that correctly display the flow of threads, and using
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>Thanks.)
>
> > I have been reading files with the following command:
> >
> > @source_lines = (<SOURCE_FILE>);
> >
> > This has worked until I started reading some very large files.
>
>This reads the entire file into the array, and should only be used for files
>that you can guarantee to be very small. As you have found, filling up your
>computer's memory isn't a good idea!
>
> > Is there a better way to read files? The files I am trying to read now are
> > about 300 megabytes in size.
>
>In most cases you will need access to only one record at a time. 
>Writing a loop
>like this
>
>while (<SOURCE_FILE>) {
>   chomp;
>   process_record($_);
>}
>
>will minimize your memory usage and almost certainly run much faster.
>
> > The bad news is that the spec has no carriage returns or line 
> feeds. We have
> > no control over the spec. I need to replace a few characters in the file.
>
>The end of each file record must be defined somehow. Either there is a
>terminating characters sequence or the records are fixed-size, or 
>possibly they
>are variable-sized with the actual size specified earlier in the file. Take
>another look at your file spec.
>
>HTH,
>
>Rob
>
>
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