regex - How to replace single quote to two single quotes, but do nothing if two single quotes are next to each other in perl -


i need change single quote found in string 2 single quotes, if more 1 single quotes found successively, should remain is.

e.g. str = abc'def''sdf'''asdf output should : str = abc''def''sdf'''asdf

i think cleanest way search following pattern:

(?<!')'(?!')

and replace 2 single quotes. pattern searches single quote, has negative lookbehind , lookahead assertions check preceeding , proceeding character not single quote.

my $var = "abc'def''sdf'"; print "$var\n"; $var =~ s/(?<!')'(?!')/''/g; print "$var\n";

note have written straight pattern match, e.g.

(^|[^'])'($|[^'])

but replacement becomes tricky because have consumed characters surrounding single quote. don't work if don't have to.

output:

abc'def''sdf' abc''def''sdf''

demo here:

rextester


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