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How do I replace a substring (if exists) with a different substring in a string?

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Contributed by kommesel on Jul 20, 2001 at 13:44 UTC
Q&A  > strings


Answer: How do I replace a substring (if exists) with a different substring in a string?
contributed by tachyon

You can use a s/// regex like this:

my $str = "I have a dream"; my $find = "have"; my $replace = "had"; $find = quotemeta $find; # escape regex metachars if present $str =~ s/$find/$replace/g; print $str;

The quotemeta lets you find strings that contain regex meta characters and the /g at the end of the s/// does all occurances.

cheers

tachyon

Answer: How do I replace a substring (if exists) with a different substring in a string?
contributed by davorg

With appropriate use of index, length and substr.

And remember that substr can be used as an lvalue.

Answer: How do I replace a substring (if exists) with a different substring in a string?
contributed by dkubb

You can use substr, length, and index inside a while loop to do what you want:

my $string = '01234567890'; my $find = '0'; my $replace = 'a'; my $pos = index($string, $find); while ( $pos > -1 ) { substr( $string, $pos, $length( $find ), $replace ); $pos = index( $string, $find, $pos + length( $replace )); }

Benchmarked, this is about 15-20% faster than a s///g regex.

IMHO, unless blazing speed is really important, you can't beat the following for readability:

  $string =~ s/\Q$find\E/$replace/g;

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