selecting characters from a variable

Juhi has asked for the wisdom of the Perl Monks concerning the following question:

hey there I am reading a file line by line... each line is stored in a scalar variable($LINE) and then i need to extract all the characters from the line till the occurrance of the first ":" in the line and also extract all chracters between the fourth ":" and the next "," in the same line.................. can anyone tell me how to do that.. i believe substr($VARNAME,N,M) returns a substring between the Nth and Mth column in a line.. So if i could just read each character in a line and count the column numbers of the first and fourth colon(":") i guess this'd be possible...but i have no clue as to how i can read the variable $LINE character by character

2006-06-04 Retitled by planetscape, as per Monastery guidelines

( keep:0 edit:12 reap:0 )

Original title: 'selecting characters from a varialble'

Comment on selecting characters from a variable

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Re: selecting characters from a variable by ptum (Priest) on Jun 02, 2006 at 13:36 UTC
It sounds to me as though you really want to do a split, parsing your string into tokens, delimited by the ':' character. `my @tokens = split /:/,$line;` [download] If you really do want to split up the line into an array of characters, you can simply use the split without a delimiting argument, which will cause your string to be split into one-character array elements. Update: As the man without a Pony indicates below, what I mean when I say 'without a delimiting argument' is this: `my @tokens = split //,$line;` [download] No good deed goes unpunished. -- (attributed to) Oscar Wilde	[reply] [d/l] [select]
Re^2: selecting characters from a variable by Fletch (Bishop) on Jun 02, 2006 at 15:03 UTC
You still need to give a pattern to split on which matches the null string (`//` or `''`) to split to characters; omitting both the pattern and what to split splits `$_` on whitespace (at least in list context; in scalar context it splits `$_` on whitespace into `@_` and you'll get griped at as it's deprecated behavior). See the docs for split for more details.</pedant>	[reply] [d/l] [select]
Re: selecting characters from a variable by thundergnat (Deacon) on Jun 02, 2006 at 15:20 UTC
`use warnings; use strict; while ( my $line = <DATA> ) { my ( $first, $fourth ) = (split(/:/, $line))[0,3]; $fourth =~ s/,.+$//; print "$first, $fourth\n"; } __DATA__ First column:Second:Third:Fourth Column, with some extra crap:Fifth First column:Second:Third:Fourth Column, with some extra crap, and eve +n more:Fifth` [download]	[reply] [d/l]
Re: selecting characters from a variable by dsheroh (Monsignor) on Jun 02, 2006 at 15:14 UTC
Assuming those two spans of characters are all you're interested in (rather than the entire line as a series of :-delimited fields), then it sounds to me like you're looking for a regex-based solution, such as: `$LINE =~ /^([^:]):[^:]:[^:]:[^:]:([^,:])/; $up_to_first_colon = $1; $fourth_colon_to_next_comma = $2;` [download] The `^([^:]):` captures all of the non-colon characters ([^:]) from the start of the line (^) until the first colon and places it in $1. Each `[^:]:` skips over a group of non-colon characters, ending with a colon. Finally, `([^,:])` captures the group of non-colon, non-comma characters following the fourth colon and places it in $2. (Change it to `([^,])` if the second field should only be terminated by a comma and not by a colon.)	[reply] [d/l] [select]
Re: selecting characters from a variable by jesuashok (Curate) on Jun 02, 2006 at 13:58 UTC
Hi `$line = "one:two:three:four:five:five"; my ( $one,$two) = (split(/:/,$line))[0,3]` [download] I am not able to understnad the following line :- and the next "," in the same line If you give me the proper input I can answer for that. "Keep pouring your ideas"	[reply] [d/l]