testing if php string is an integer

Question

$post is used to simulate $_POST, and I found that $_POST['int'] is a string.

How can I tell whether $post['int'] is an integer?

The following indicates that it is not an integer.

<?php
  $post=array('int'=>(string)123);
  var_dump($post);
  echo(is_int($post['int'])?'int':'not int');
?>

EDIT. Per the documentation (http://php.net/manual/en/function.is-int.php), is_int — Find whether the type of a variable is integer, so obviously it does exactly what it is suppose to do. Still need to tell whether the string is an integer...

Answer 1

If you really want to know if the value is an integer you can use filter_input(). Important: you can not test this with a fake $_POST var, you really have to post the value or use INPUT_GET for testing and append ?int=344 to your URL

// INPUT_POST => define that the input is the $_POST var
// 'int' => the index of $_POST you want to validate i.e. $_POST['int']
// FILTER_VALIDATE_INT => is it a valid integer
filter_input( INPUT_POST, 'int', FILTER_VALIDATE_INT );

Working example:

<form action="" method="post">
    <input type="text" name="int" />
    <input type="submit" />
</form>
<?php
if( isset( $_POST["int"] ) ) {
    echo( filter_input( INPUT_POST, 'int', FILTER_VALIDATE_INT )  ) ? 'int' : 'not int';
}

Update: Due to the comment of @user1032531's answer

I would have thought a baked-in solution would have been available

There is a built in function called filter_var(), that function does the same like the above example, but it doesn't need a POST or GET, you can simply pass a value or variable to it:

var_dump( filter_var ( 5, FILTER_VALIDATE_INT ) );// 5
var_dump( filter_var ( 5.5, FILTER_VALIDATE_INT ) );// false
var_dump( filter_var ( "5", FILTER_VALIDATE_INT ) );// 5
var_dump( filter_var ( "5a", FILTER_VALIDATE_INT ) );// false