PHP regex - valid float number

Question

I want user only input 0-9 and only once "."

 patt = /[^0-9(.{1})]/

 1.2222 -> true
 1.2.2  -> false (only once '.')

help me , thank !

Answer 1

You can use is_numeric() with the caveat that it accepts a bit more than one usually wants (e.g. 1e4).

Answer 2

Why not just use is_numeric if you're not experienced with regular expressions.

As to your regex: . matches all characters, \. matches a dot. {1} is not necessary. And I have no clue what you're trying to do with [^ ... ]. Read the regular expressions tutorial if you really want to use regular expressions somewhere in your code.

Answer 3

Why not use http://php.net/manual/en/function.is-float.php ? But anyhow, the RegEx would be ^[\d]+(|\.[\d]+)$ have fun!

Answer 4

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

This matches normal floats e.g. 3.14, shorthands for decimal part only e.g. .5 and integers e.g. 9 as well as negative numbers.

Answer 5

this is what you're looking for

$re = "~        #delimiter
    ^           # start of input
    -?          # minus, optional
    [0-9]+      # at least one digit
    (           # begin group
        \.      # a dot
        [0-9]+  # at least one digit
    )           # end of group
    ?           # group is optional
    $           # end of input
~xD";

this only accepts "123" or "123.456", not ".123" or "14e+15". If you need these forms as well, try is_numeric

Answer 6

Regular Expressions are for matching string patterns. If you are not explicitly after validating the input string's format (but the actual value), you can also use

filter_var("1.33", FILTER_VALIDATE_FLOAT);

to make sure the input can be used as a float value. This will return FALSE if it is not a float and the float or integer value otherwise. Any type juggling rules apply.

Answer 7

This regex:

\d*(?:\.\d+)?

will give results:

123 -> true
123.345 -> true
123. -> true
.345 -> true
0.3345 -> true

However, you must check emptiness of the input before using it because the regex also permit zero-length input.