Newbie: Regular expresion

[Jose Luis]

Hi,

Given the string "one;two;three;four...", is there a easy way to
print "one":


$ echo "one;two;three;four..."|perl -e 'while(<>){$_ =~ /^(.*)(\(.*)
$/ && print $1}'
one;two;three



Thanks in advance,
Jose Luis

 

[Jürgen Exner]

Given the string "one;two;three;four...", is there a easy way to
print "one":

use strict; use warnings;
my $s = "one;two;three;four...";
print ((split(/;/, $s))[0]);

jue

 

[Peter Makholm]

Given the string "one;two;three;four...", is there a easy way to
print "one":

Not using regular expressions I would use the split function to
archieve this.

$ echo "one;two;three;four..."|perl -e 'while(<>){$_ =~ /^(.*)(\(.*)
$/ && print $1}'
one;two;three

But what you are missing is the non-greedy variant of the initial
*. By default quantifiers af greedy, that is that they match as much
as posible. If you instead uses (.*?) it will match as little as
posible.

Another soulution woulb be to replace (.*) with ([^;]*). This matches
as many non-semicolon as possible.

//Makholm

 

[Jürgen Exner]

Not using regular expressions I would use the split function to
archieve this.

Actually the first argument to split() is a regular expression.
But I do strongly share your sentiment about using split() for this task
instead of capturing RE groups.

jue

 

[Steve C]

Hi,

Given the string "one;two;three;four...", is there a easy way to
print "one":


$ echo "one;two;three;four..."|perl -e 'while(<>){$_ =~ /^(.*)(\(.*)
$/ && print $1}'
one;two;three

Use 'sed mode':

echo "one;two;three;four..."|perl -pe 's/;.*//'
one

autosplit lets you pick other than first element:

echo "one;two;three;four..."|perl -lanF';' -e'print $F[1]'
two