Use Perl.

Post #204,957 by ben_tilly 4/27/05 2:27:08 PM Reply	Use Perl. Are they always in order and the values guaranteed to be true? If so, then the following hack will work: \nperl -pe 'if (/^foo(\\d+)=(.\\n)/) {$r \|\|= $2; $_="foo4=$r" if 4==$1;}' testdata\n If the values are not guaranteed to be true, then you have to check whether $r is defined before assigning to it. If they are not always in order then I'd need to run 2 passes and would want to write a simple script to do it. Cheers, Ben I have come to believe that idealism without discipline is a quick road to disaster, while discipline without idealism is pointless.* -- Aaron Ward (my brother)
Post #205,134 by boxley 4/28/05 2:45:30 PM Reply	have time for some education? `perl -pe 'if (/^foo(\\d+)=(.\\n)/) {$r \|\|= $2; $_="foo4=$r" if 4==$1;}' testdata` notice I am using ttffp tags now I want to be sure I clearly understand what is going on. I throw my file at this string perl -pPrint -eEdit single tick to resolve the following enclosed actions if (what is the / before the first foo? ^foo followed by a decimal place holder and has a . followed by a newline and the closing /? $r is replace \|\| (why the 2 pipes? $2 being the second field $_"foo4=$r(eplaced value) if 4 is exactly equal to $1 the first field. ending tick corrections and information gladly accepted, thanx, bill All tribal myths are true, for a given value of "true" Terry Pratchett [link\|http://boxleys.blogspot.com/\|http://boxleys.blogspot.com/] Any opinions expressed by me are mine alone, posted from my home computer, on my own time as a free american and do not reflect the opinions of any person or company that I have had professional relations with in the past 48 years. meep questions, help? [link\|mailto:pappas@catholic.org\|email pappas at catholic.org]
Post #205,169 by ben_tilly 4/28/05 6:47:41 PM Reply	Here is the same code, commented \n#!/usr/bin/perl -p\n# The -p switch, as explained in perlrun, reads each\n# line into $_, runs your code, then prints $_.\n# More precisely it puts a loop like this around your\n# code:\n#\n# LINE:\n# while (<>) {\n# ... # your program goes here\n# } continue {\n# print or die "-p destination: $!\\n";\n# }\n#\n# The -p switch allows you to edit lines on the fly by\n# editing $_.\n#\n# Previously I used -e to allow the program to go on\n# the command line, but this time around I am not\n# doing that.\n\nif (\n / # This regular expression matches:\n ^ # the start of the string\n foo # then foo\n (\\d+) # then some digits, put in $1\n = # an = sign\n (.\\n) # other junk, including a return\n # that go into $2.\n /x # /x turns on commenting.\n # (since no variable is bound to the\n # match it matches $_ - which is\n # conveniently your current line.)\n) {\n # OK, we matched. If we have not yet come up with\n # a replacement for foo4, then set it to $2.\n $r \|\|= $2;\n # If this is foo4, then replace $_ (the new value is\n # what we'll print).\n $_ = "foo4$r" if 4 == $1;\n}\n Cheers, Ben I have come to believe that idealism without discipline is a quick road to disaster, while discipline without idealism is pointless.* -- Aaron Ward (my brother)
Post #205,178 by boxley 4/28/05 7:58:31 PM Reply	thank you very much knowing how it works sort of is no where near as good as knowing exactly why it works so can put that to use elsewhere, thanx, bill All tribal myths are true, for a given value of "true" Terry Pratchett [link\|http://boxleys.blogspot.com/\|http://boxleys.blogspot.com/] Any opinions expressed by me are mine alone, posted from my home computer, on my own time as a free american and do not reflect the opinions of any person or company that I have had professional relations with in the past 48 years. meep questions, help? [link\|mailto:pappas@catholic.org\|email pappas at catholic.org]

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