some questions about metacharacters.. and their usage

[dsaba]

yay! finally the question/s you've been waiting for!

-It's not too specific on "how do I fix bla bla, in my own specific project..bla bla"

-Its general enough to help onlookers on regex questions in general

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I want to match something like this:

<meta name="stapler" content="Whatever 39.32" />

 

the part that will change that I cannot take literally will be the "39.32"

So you can basically think of it like this:

literal text - any number of chars less than 50 - literal text

 

sounds pretty easy right? I thought so too. Here's my attempt:

$pattern = "~literal text .+{1,50} literal text~";

 

all I want to say is match any characters and 50 or less of them

 

i've seen it written this way before:

(.*?){0,200}

the dot means 1 single char of any kind

the asterisk means 0 or more of these characters

and the question mark means optional of these characters, meaning it can be 0??

 

instead of putting the ? mark there why not just leave it as:

(.*)  -- I mean doesn't the 0 or more part basically say its optional too? Since there can be 0

 

 

I don't quite get the brackets either if someone could explain, when and when not to use them, i tried saying: .*{0,50}

but this gave some repitition error..etc..

 

 

-thanks

[BenInBlack]

* means - Zero or more of 'n'

{0,50} mean Zero to 50 of 'n'

 

you can combine them it is either

.* or .{0,50}

 

here is a regex tester I like to use http://www.quanetic.com/regex.php

 

 

[dsaba]

I want to match the "123"

 

whatever 123 this

~whatever .* this~

 

~whatever (.){0,50} this~

 

none of these work, what will?

[effigy]

and the question mark means optional of these characters, meaning it can be 0??

 

No. When a question mark follows a quantifier it makes it ungreedy (lazy).