PHP函数is_int（）有什么用？

I just wonder why php have a function like is_int(). Documentation says that

To test if a variable is a number or a numeric string (such as form input, which is always a string)

I am sure that no one will ever have to check the type of a variable that is statically assigned. So someone please tell me will there be any situation, where the function is_int() really useful ?

complete understding soluation....

this is code

 <?php
  $values = array(23, "23", 23.5, "23.5", null, true, false);
  foreach ($values as $value) {
   echo "is_int(";
  var_export($value);
    echo ") = ";
       var_dump(is_int($value));
     }
       ?>

this is output

     is_int(23) = bool(true)
     is_int('23') = bool(false)
    is_int(23.5) = bool(false) 
   is_int('23.5') = bool(false) 
     is_int(NULL) = bool(false)
    is_int(true) = bool(false)
      is_int(false) = bool(false)

This function can be useful in the following scenario,

$a = 5;


//some functionality
function passbyref(&$b)
{
    $b = "45";
}


passbyref($a);


if(is_int($a))
{
   print "Yes it is int";
}

It finds whether the type of the given variable is integer or not.

This is the example I found :

$values = array(23, "23", 23.5, "23.5", null, true, false);
    foreach ($values as $value) {
        echo "is_int(";
        var_export($value);
        echo ") = ";
        var_dump(is_int($value));
    }

The above example will output:

is_int(23) = bool(true)
is_int('23') = bool(false)
is_int(23.5) = bool(false)
is_int('23.5') = bool(false)
is_int(NULL) = bool(false)
is_int(true) = bool(false)
is_int(false) = bool(false)

To understand more : Click here

Consider a user form input:

$_POST['integer'] = "3";
$integer = +$_POST['integer']; // convert to a number
var_dump(is_int($integer)); // bool(true)

$_POST['float'] = "3.5";
$float = +$_POST['float']; // convert to a number
var_dump(is_int($float)); // bool(false)