lazy quantifiers

[eidalina20]

hey everyone.. can someone please answer this question for me and provide me with some examples if possible.. i am new to all of this sso just trying to learn.

I have this statement:

The regular expression closure operators * and + are also known as quantifiers. Many current regular expression packages in languages like Perl and Java distinguish between greedy quantifiers (denoted by * and +) which match the maximum number of their operand in order to match what follows the quantifier and lazy quantifiers (denoted by *? and +?) which match the minimum number of matches for their operand in order to match what follows the quantifier.

Can someone please provide me with a practical example which illustrates the need for lazy quantifiers.


thank you =)

[Marc G]

For performance maybe.
When you write the regular expression "ab.+" (without the quotes obviously), you want to find a string that starts with a followed by 1 or more b's.
If you run this query on "wwwabbbbbcc", in lazy mode, it can stop parsing after the first b because then you have an a followed by 1 b which matches the query. However, in greedy mode, the parser has to parse all the way up to the character c.

[eidalina20]

For performance maybe.
When you write the regular expression "ab.+" (without the quotes obviously), you want to find a string that starts with a followed by 1 or more b's.
If you run this query on "wwwabbbbbcc", in lazy mode, it can stop parsing after the first b because then you have an a followed by 1 b which matches the query. However, in greedy mode, the parser has to parse all the way up to the character c.

Thank you Marc =)

[Kheun]

This is an excellent tutorial for regex.
http://www.regular-expressions.info/