Find the position of substring

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

Hi,

I have one string and its substring and would like to find which is the position of the words that match the substing. For instance, for the string:

this is a test

and the substing

is a test

I want to have as output the

2 3 4

Here is my code but is returs me the number of the first charachter.

my $str = "this is a test";</p>
my $sub = "is a test";
if ($str =~ /\b$sub\b/) {
    
    print "match at char ",@-[0], "\n";
}
[download]

Any help would be useful.

Tahnks

Comment on Find the position of substring Select or Download Code

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Re: Find the position of substring by hdb (Monsignor) on Apr 22, 2015 at 11:59 UTC
Your result only depend on the number of words before your substring and the number of words in the substring: `use strict; use warnings; my $string = 'this is a test'; my $substr = 'is a test'; if( $string =~ /(.*)\b$substr\b/ ) { # do we have a match? my $n = () = $1 =~ /\b(\w+)\b/g; # number of words before mat +ch my $m = () = $substr =~ /\b(\w+)\b/g; # number of words in match print join(' ',$n+1..$n+$m),"\n"; }` [download]	[reply] [d/l]
Re^2: Find the position of substring by Anonymous Monk on Apr 22, 2015 at 12:28 UTC
Thanks! It works :)	[reply]
Re: Find the position of substring by Laurent_R (Canon) on Apr 22, 2015 at 17:59 UTC
Rather than regexes, you could also use the index, split and substr built-ins, as shown in the following session under the debugger: `DB<1> $str = "this is a test"; DB<2> $sub = "is a test"; DB<3> $index = index $str, $sub; DB<4> $nr_before = scalar split /\s+/, substr $str, 0, $index; DB<5> p $nr_before; 1 DB<6> $nr_in = scalar split /\s+/, $sub ; DB<7> p $nr_in; 3 DB<8> print ++$nr_before, " " for 1..$nr_in; 2 3 4` [download] Note: I know that the call to the scalar built-in is not really useful in a scalar context, but I thought it would clarify the idea. Je suis Charlie.	[reply] [d/l]