PHP regex unexpected match

Question

i have a regex in my php code that should match every number and all "operators" +-*/^r() my regex looks like this

/(?:(\d+(?:\.\d+)|(\+)|(-)|(\*)|(\/)|(\^)|(r)|($)|($)))/

and when tested with the string preg_match_all($expression,"2+2",$results) it gives me back

Array
(
    [0] => Array
        (
            [0] => '+'
        )

    [1] => Array
        (
            [0] => ''
        )

    [2] => Array
        (
            [0] => '+'
        )

    [3] => Array
        (
           [0] => ''
        )

    [4] => Array
        (
            [0] => ''
    )

    [5] => Array
        (
            [0] => ''
        )

    [6] => Array
        (
            [0] => ''
        )

    [7] => Array
        (
            [0] => ''
        )

    [8] => Array
        (    
            [0] => ''
        )

    [9] => Array
        (
            [0] => ''
        )

)

When (if it works right) i should be getting this

Array
(
    [0] => Array
        (
            [0] => '2'
            [1] => '+'
            [2] => '2'
        )

    [1] => Array
        (
            [0] => '2'
            [1] => ''
            [2] => '2'
        )

    [2] => Array
        (
            [0] => ''
            [1] => '+'
            [2] = > ''
        )

    [3] => Array
        (
           [0] => ''
           [1] => ''
           [2] => ''
        )

    [4] => Array
        (
           [0] => ''
           [1] => ''
           [2] => ''
        )
    ...

)

Note, it returns similar behaviour for all of the operators, it seems to ignore the numbers entirely

Note, I DO need separate capture groups so i have different match indexes for each result

"should match every number and all "operators" +-*/^r()" i am trying to tokenize based on this regex — NathanFrasier
– NathanFrasier, Commented Jul 12, 2013 at 14:59
sorry, somewhat new to regex, you mean rather than my current i should use what instead? maybe post an answer rather than a comment — NathanFrasier
– NathanFrasier, Commented Jul 12, 2013 at 15:02
@casimiretHippolyte sorry, upon looking into it, i do need separate capture groups, because i need a 2D array separated on the indexes of each result, i need to take a different action depending on the token and i'd rather match strings once and be done — NathanFrasier
– NathanFrasier, Commented Jul 12, 2013 at 15:14

Casimir et Hippolyte · Accepted Answer · 2013-07-12 16:14:30Z

1

you can simply do this:

$pattern = '~\d+(?:\.\d+)?|[-+*/^r()]~';

edited Jul 12, 2013 at 16:14

answered Jul 12, 2013 at 15:02

Casimir et Hippolyte

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2 Comments

NathanFrasier Over a year ago

dont the -^() all need to be escaped?

Casimir et Hippolyte Over a year ago

@Nanos: You don't need to escape these characters inside a character class. ~ is the pattern delimiter (as / or #)

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