RegEx to match comma separated numbers with optional decimal part

by

This:

\d{1,3}(,\d{3})*(\.\d\d)?|\.\d\d

matches all of the following numbers:

1
12
.99
12.34 
12,345.67
999,999,999,999,999.99

If you want to exclude numbers like 123a (street addresses for example), or 123.123 (numbers with more than 2 digits after the decimal point), try:

(?<=\s|^)(\d{1,3}(,\d{3})*(\.\d\d)?|\.\d\d)(?=\s|$)

A little demo (I guessed you’re using PHP):

$text = "666a 1 fd 12 dfsa .99 fds 12.34 dfs 12,345.67 er 666.666 er 999,999,999,999,999.99";
$number_regex = "/(?<=\s|^)(?:\d{1,3}(?:,\d{3})*(?:\.\d\d)?|\.\d\d)(?=\s|$)/";
if(preg_match_all($number_regex, $text, $matches)) {
  print_r($matches);
}

which will output: 

Array
(
    [0] => Array
        (
            [0] => 1
            [1] => 12
            [2] => .99
            [3] => 12.34
            [4] => 12,345.67
            [5] => 999,999,999,999,999.99
        )

)

Note that it ignores the strings 666a and 666.666

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