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File open, read, write test example
File Handling example from a Well House Consultants training course
More on File Handling [link]
Source code: fsv Module: P207
# File open, read, write test example
# Test that the output file won't clobber an old one # And if that's OK open inputs and outputs if (-e "file.file") { $sz = -s "file.file"; $tm = -M "file.file"; print STDERR "Size $sz b, updated $tm days ago\n"; die "I'm not going to be that brutal\n"; } open (FH,"../requests.xyz") or die "No input file\n"; open (FHO,">file.file") or die "Wrong - can't write\n"; # Copy lines including "Perl" to the screen and other lines # to output file, counting the lines as you do so $np = $nl = 0; while ($lyne = <FH>) { if ($lyne =~ /Perl/) { print "PERL! $lyne"; $np++; } else { print FHO $lyne; } $nl++; } # Close both files and report on the work done # Note that report is supressed if STDOUT redirects to file close FH; close FHO; -t STDOUT and print "Job Completed. Found $np out of $nl\n"; # Finally, provide user documentation through POD! __END__ This example taught on Well House Consultants Perl course - written for Delegates on October 2007. See http://www.wellho.net/course/lpfull.html graham@wellho.net / +44 (0) 1225 708225 =head1 Example of file handling in Perl This example program shows the various elements of a Perl program to tes, open, read and write files. The file requests.xyz from the parent directory is opened (if it exists) for input. The file file.file in the current directory is opened (if it does NOT exist) for output; if it already exists, the program exits with an error message after reporting critical status data. Data is read line by line and copied from input to output if it does NOT include the word "Perl"; if it does, the line is echoed to the screen. Both files are closed, and if the output device STDOUT is interactive (window rather that file) a report line of the work done is added. =cut Learn about this subject
This module and example are covered on the following public courses:
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Other Examples
This example comes from our "File Handling" training module. You'll find a description of the topic and some
other closely related examples on the "File Handling" module index page.
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