preg_split error

[The Little Guy]

$final = '5+5^2';
$terms = preg_split('~(+|-|*|/)~',$final);
print_r($terms);

 

Warning:  preg_split() [function.preg-split]: Compilation failed: nothing to repeat at offset 1 in /home/.marble/ryannaddy/dudeel.com/results/toolsCalculator.php on line 24

[corbin]

\+

 

 

Got to escape that.

[discomatt]

You also have to escape the * (\*)

 

A better regex (you don't have to escape in character classes):

 

$final = '5+5^2';
$terms = preg_split('~[+*/-]~',$final);
print_r($terms);

 

You should avoid using the or ( | ) operator at all costs

[nrg_alpha]

Little Guy,

 

That's the beauty of using character classes vs alternations... not only is it faster, but any meta characters listed within a character class loses their special meanings and become literals (except for example: the placements of characters like ^ or -... depending on their location within the class, their meanings change). Characters like backslash will still need to be escaped in a character class (\ becomes \\\).

 

And on that note.. if you want to use a dash as a character in a character class (and not a range as in 0-9), always list the dash either as the first or last character in the character class. Otherwise, regex will see it as a range (correct dash placement is seen in discomatt's example).

[discomatt]

I'd like to note, dashes (-) can be anywhere in a character class, but if they're anywhere other than the end or beginning, you must escape them.

 

[abc\-123]

[nrg_alpha]

I'd like to note, dashes (-) can be anywhere in a character class, but if they're anywhere other than the end or beginning, you must escape them.

 

[abc\-123]

 

Ah, I did neglect to mention that

But in truth, if you list the dash first or last, there will never be the need to escape it.