How can I make part of a Perl regular expression optional? [duplicate]

This question already has answers here: How can I make part of regex optional? (2 answers) Closed 3 months a开发者_JS百科go.

I want match

 my @array = ( 'Tree' , 'JoeTree');

    foreach (@array ) {
      if ( $_ =~ /^(Joe)Tree/gi) {
        print "matched $_";
      }
    }

It matching only JoeTree. It's not matching Tree ?

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Try:

if (/^(?:Joe)?Tree/gi)

• We've made the Joe part optional.
• Also you can change (..) to (?:...) as you are just grouping.
• Also $_ =~ part is redundant as by default we check in $_

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You missed a ?: /^(Joe)?Tree/gi