Regular Expressions - what does it mean?

Pigmaster

I am playing with BBCode and need to understand Regular Expressions.

I have found 2 examples to start with and these are the bold tags but I can not identify what the difference between the 2 examples.

I have been told they do the exact same function.

I have tried looking at Regualr Expression tutorials on the net and I understand some of what I have read but I can not find out what...
The / mean in the first example (beginning and end of expression)?
The / mean in the second example (beginning and end of expression)?
The is (/is ot #is) on the end of the examples mean?

/\[b\](.*?)\[\/b\]/is

#\[b\](.*?)\[/b\]#is

Thanks very much

YAOMK

The "/" and the "#" are Perl like regular expression delimiters (the former is the traditional delimiter and the later is user defined). The /is are modifiers, the "i" is for case insensitive and the "s" for single-line mode.

Pigmaster

Thanks for the info, this does help to explain alot.

Thanks

YAOMK

no prob.

nrg_alpha

YAOMK;10895879 wrote:
the "s" for single-line mode.

The /s is actually 'dot-machtes-all match mode', so that the dot character in the pattern (not within a character class however) takes into account newlines, where as by default, it doesn't.

YAOMK

nrg_alpha is right. The /s may be referred to as single-line mode or dot-machtes-all match mode, the later seems to be far more popular, so when looking up information about it, you may as well use it.