Please, i'm learning regex, i don't really understand this expression e.g to replace image: <img src="http://google.com/image.jpg"/> with bbcode:
/\[img\](.+?)\[\/img\]/ig

Please, what does the (.+?) mean? explain to me bit by bit with examples, and why $1 coming as a variable? And i see $2 sometimes in some expressions... Your goodness of heart will be appreciated thank you.

What (.+?) Means is 'Match any character that comes btween the [img] one or more times'

. Signifies any character

+ signifies one or more of the previous characters

? Is match the previous character if there is a match I.e if + had a match ..else it would not match anything).



The variable,$1 is used in saving the matched word from the regex

$2 ___ same thing as above

Jregz:
What (.+?) Means is 'Match any character that comes btween the [img] one or more times'

. Signifies any character

+ signifies one or more of the previous characters

? Is match the previous character if there is a match I.e if + had a match ..else it would not match anything).



The variable,$1 is used in saving the matched word from the regex

$2 ___ same thing as above

Thank you very much.
Then what about the brackets (.+?)

webninja:

Thank you very much.
Then what about the brackets (.+?)

Brackets are used to capture texts from a pattern in other to apply it's mached result (those in the parenthesis) to the rest of the regex..you could have a regex that wants to match the word 'clown' (or any other word) four times,you enclose the first regex that searches for a string in a parenthesis then apply the text mathed to the rest of the regex (the same regex)..they are usually available in \1 and so on

Jregz:


Brackets are used to capture texts from a pattern in other to apply it's mached result (those in the parenthesis) to the rest of the regex..you could have a regex that wants to match the word 'clown' (or any other word) four times,you enclose the first regex that searches for a string in a parenthesis then apply the text mathed to the rest of the regex (the same regex)..they are usually available in \1 and so on

Ok, thanks man, now how do the $2 come in? Please show some code example

webninja:

Ok, thanks man, now how do the $2 come in? Please show some code example

$2 means that the regex machine should capture the 2nd group in the String

Example
String ="I amam brotherbrother";

Regex Pattern to match the repeated String would be:

(\w+)$1\s(\w+)$2

Explanation

The first (\w+) would match [am]
Then $1 would also match the next [am].

Same thing goes with [brother]
The second (\w+) matches the first [brother]
Then $2 matches the [brother] after the first [brother]