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While Loops

by blue_cowdawg (Monsignor)
on Jan 08, 2013 at 18:50 UTC ( #1012309=note: print w/ replies, xml ) Need Help??


in reply to While Loops

If I am understanding you question correctly, how about:

#!/usr/bin/perl -w use strict; my @data=(); my $file='c:\text.txt'; open FILE,"< $file" or die "$file: $!"; while (my $line =<FILE> && scalar $#data < 100){ chomp $line; push @data,[split /\t/,$line]; }


Peter L. Berghold -- Unix Professional
Peter -at- Berghold -dot- Net; AOL IM redcowdawg Yahoo IM: blue_cowdawg


Comment on While Loops
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Re: While Loops
by Anonymous Monk on Jan 08, 2013 at 18:53 UTC

    I would like to read the 1st 100 records from the text file, print them, and read the next 100 and print them, etc until I run out of record in the text file

      With the improved spec, you'd want something more like:

      #!/usr/bin/perl -w use strict; my @data=(); my $file='c:\text.txt'; open my $fh,"<", $file or die "$file: $!"; while (my $line = <$fh>){ push @data, $line; if (@data == 100) { print @data; @data = (); } } print @data;

      #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

      #!/usr/bin/perl -w use strict; my @data=(); my $file='c:\text.txt'; my $count=0; open FILE,"< $file" or die "$file: $!"; while (my $line =<FILE> ){ chomp $line; push @data,[split /\t/,$line]; $count++; next if $count < 99; while ($#data >= 0 ) { printf "%s\n",join(",",shift @data); } $count = 0; }
      So.. how much more of your homework do you need me to do?


      Peter L. Berghold -- Unix Professional
      Peter -at- Berghold -dot- Net; AOL IM redcowdawg Yahoo IM: blue_cowdawg

      we're really guessing at what you are trying to do, so in that spirit maybe here's a real life example that has enough stuff in it to be useful on a few fronts...


      test file
      #ls -la > test.txt ... abreviated

      -rw-r--r--  1 OQ91   Domain Users   273532 Sep 25 15:29 spy.csv.bak
      -rw-r--r--  1 OQ91   Domain Users    14704 Jan  8 12:08 spy.sdf
      -rw-r--r--  1 OQ91   Domain Users     4329 Oct 17 10:28 spy.sdf.bak
      -rwxr-xr-x  1 OQ91   Domain Users  1196465 Sep 26 03:36 spywork.ods
      -rw-r--r--  1 OQ91   Domain Users   312739 Jan  8 09:40 spyx.csv
      -rwxrwxr-x  1 OQ91   Domain Users     4875 Dec 26 22:05 stone.pl
      -rwxr-xr-x  1 OQ91   Domain Users     2396 Oct 25 09:57 stone.pl.121025
      -rwxr-xr-x  1 OQ91   Domain Users     3375 Oct 29 10:27 stone.pl.121026
      -rwxr-xr-x  1 OQ91   Domain Users     3811 Oct 29 07:52 stone.pl.121029
      -rwxr-xr-x  1 OQ91   Domain Users     3809 Nov  8 11:06 stone.pl.121108
      -rwxr-xr-x  1 OQ91   Domain Users 77687808 Sep 26 03:46 Taylor_Book_08.xls
      -rw-r--r--  1 OQ91   Domain Users     9095 Dec 26 22:14 test15.pl
      -rw-r--r--  1 OQ91   Domain Users     4350 Nov  7 01:07 test15.pl.121107
      -rw-r--r--  1 OQ91   Domain Users     4424 Nov  7 11:57 test15.pl.121107a
      -rw-r--r--  1 OQ91   Domain Users     8630 Nov  7 13:57 test15.pl.121107b
      -rw-r--r--  1 OQ91   Domain Users     9039 Nov  8 08:59 test15.pl.121108
      -rw-r--r--  1 OQ91   Domain Users     9156 Dec 26 22:10 test15.pl.121226
      -rw-r--r--  1 OQ91   Domain Users    46987 Dec  4 13:25 zzz.out
      
      $ cat test.txt | perl -l -n -e 'BEGIN {$x="OQ91";$linecount=0;$sum=0;} if((split)[2]==$x){$linecount++ ;$sum += (split)[5]; printf "%s\t %s\t\t %s\n",(split)[2],(split)[5],(split)[9]} ; END {printf "linecount: %d  Sum: %d",$linecount,$sum}'

      Here's some output... abreviated

      OQ91     312739          spyx.csv
      OQ91     4875            stone.pl
      OQ91     2396            stone.pl.121025
      OQ91     3375            stone.pl.121026
      OQ91     3811            stone.pl.121029
      OQ91     3809            stone.pl.121108
      OQ91     77687808                Taylor_Book_08.xls
      OQ91     9095            test15.pl
      OQ91     4350            test15.pl.121107
      OQ91     4424            test15.pl.121107a
      OQ91     8630            test15.pl.121107b
      OQ91     9039            test15.pl.121108
      OQ91     9156            test15.pl.121226
      OQ91     46987           zzz.out
      linecount: 61  Sum: 88200728
      

      sums the 5th column if the tests are true, counts the lines... prints the 2nd, 5th and 9th columns, AND it's a one liner...

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