Php only numbers Validating function - php

Question

I would like to create a validate function for numbers only, actually I have those ones that works fine, and I tried to create one myself, but it's unfortunately not working. Here are the alphanumeric and others working fine :
// Validators
private function custom($validator, $value)
{
return call_user_func($validator, $value, $this->request, $this->id);
}
private function alphanumeric($value, $custom)
{
return preg_match('/^(['.$custom.'a-z0-9_]*)$/i', $value);
}
private function valid_email($value)
{
return preg_match('/^\S+#\S+\.\S+$/', $value);
}
And the one I tried to create by modifying the alphanumeric one :
private function numbers_only($value, $custom)
{
return preg_match('/^(['.$custom.'0-9_]*)$/i', $value);
}
What's wrong with this one ?
EDIT :
I also have a JS helping with the form, for alphanumeric it's :
Form.prototype.alphanumeric = function(value, custom)
{
return !value.replace(new RegExp('['+custom+'a-z0-9_]', 'ig'), '').length;
};
What would be the JS for numeric only ?

Answer 1

Use
is_numeric($value);
return is true or false

Answer 2

If you want only numbers, remove the $custom part from the function. The /i implies case-insensitive matching, which is not relevant for numeric matches, and so can be removed.
private function numbers_only($value)
{
return preg_match('/^([0-9]*)$/', $value);
}
The expression above will match zero or more numbers, so blank input is allowed. To require at least one number, change * to + as in
return preg_match('/^([0-9]+)$/', $value);
And the [0-9]+ can be abbreviated as \d+. Since you are not capturing the value inside a an array of matches, there is no need for the extra overhead which is added by including the () capture group. That can be omitted as well.
return preg_match('/^\d+$/', $value);
Or skip the regex entirely...
Finally, if you've gotten this far and are matching only integers, it is far easier and less resource-intensive to just do:
// If you really intend to match numbers only, and not all numeric values
// which might include .,
function numbers_only($value)
{
return ctype_digit(strval($value));
}

Answer 3

In PHP, for a "only numbers" validation you can use different approaches:
is_int or is_integer
is_numeric
regular expressions
ctype_digit
filter_var
is_integer()
for this function these values are are not valid: "0010", "123"
is_numeric()
for this function these values are valid: 1.3, +1234e44 and 0x539
filter_var()
for this function a value as "00123" is not valid
CONSLUSION
it seems that only regex and ctype_digit work always fine.
TEST
a simple test here