Replace repeating characters with one with a regex

Question

I need a regex script to remove double repetition for these particular words..If these character occurs replace it with single.

/[\s.'-,{2,0}]

These are character that if they comes I need to replace it with single same character.

Answer 1

Is this the regex you're looking for?

/([\s.'-,])\1+/

Okay, now that will match it. If you're using Perl, you can replace it using the following expression:

s/([\s.'-,])\1+/$1/g

Edit: If you're using :ahem: PHP, then you would use this syntax:

$out = preg_replace('/([\s.\'-,])\1+/', '$1', $in);

The () group matches the character and the \1 means that the same thing it just matched in the parentheses occurs at least once more. In the replacement, the $1 refers to the match in first set of parentheses.

Note: this is Perl-Compatible Regular Expression (PCRE) syntax.

From the perlretut man page:

Matching repetitions

The examples in the previous section display an annoying weakness. We were only matching 3-letter words, or chunks of words of 4 letters or less. We'd like to be able to match words or, more generally, strings of any length, without writing out tedious alternatives like \w\w\w\w|\w\w\w|\w\w|\w.

This is exactly the problem the quantifier metacharacters ?, *, +, and {} were created for. They allow us to delimit the number of repeats for a portion of a regexp we consider to be a match. Quantifiers are put immediately after the character, character class, or grouping that we want to specify. They have the following meanings:

• a? means: match 'a' 1 or 0 times

• a* means: match 'a' 0 or more times, i.e., any number of times

• a+ means: match 'a' 1 or more times, i.e., at least once

• a{n,m} means: match at least "n" times, but not more than "m" times.

• a{n,} means: match at least "n" or more times

• a{n} means: match exactly "n" times