Description:
------------
hi PHP
I write a function. only numbers turn true. but it returns true when you get parameter add the # character
 
test.php file code :
 

why does it give such an error? I just detected the # character.
please help me, what is the problem?. have a nice day :)

testing info : XAMPP & PHP 7.3.1 & x64 win10 & chrome 78

Test script:
---------------
// test.php 
function number_is_valid($get_data){
    return ( preg_match('/[^0-9]/', $get_data) ) ? "NO" : "YES";
}
 
$data = $_GET['number'];
$result = number_is_valid($data);
 
print_r($result);
 

Testing results :

test.php?number=a4
// result NO
 
test.php?number=4
// result YES
 
test.php?number=4#
// result YES
 
test.php?number=4#@#
// result YES
 
but no problem with data from variable
 
$data = "4#";
$result = number_is_valid($data);
// result NO