http://www.perlmonks.org?node_id=1005584


in reply to Regex Question

G'day shealyw2,

index is another option:

Update: Oops! Left off the POSITION (index STR,SUBSTR,POSITION). Thanks, Ratazong. Here's an improved version. 

$ perl -Mstrict -Mwarnings -E '
my $x = "abc";
say $x if index($x, "a", 2) == 2;
my $y = "cba";
say $y if index($y, "a", 2) == 2;
my $z = "aba";
say $z if index($z, "a", 2) == 2;
'
cba
aba

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$ perl -Mstrict -Mwarnings -E '
my $x = "abc";
say $x if index($x, "a") == 2;
my $y = "cba";
say $y if index($y, "a") == 2;
'
cba

[download]

Note: index is based at zero (1st char = 0; 3rd char = 2)

-- Ken

Replies are listed 'Best First'.
Re^2: Regex Question
by Ratazong (Monsignor) on Nov 26, 2012 at 08:30 UTC
    Your index won't work in case there is an a before the third position, e.g. in the string aba. If you (really) want to use index, use the 3-argument-form instead: 
    
$x = "aba";
print "$x\n" if index($x, "a", 2) == 2;

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    HTH, Rata
[reply]
[d/l]

      ++ Thanks Ratazong. You're absolutely correct. I've updated my node.

      -- Ken

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