Question

I am trying to do a basic operation: to check whether string is a number.

This does not work:

$qty = $_REQUEST[qty];
if (is_int($qty) == FALSE) {
  echo "error";
} else {
  echo "ok";
}

This one does:

$qty = 1;
if (is_int($qty) == FALSE) {
  echo "error";
} else {
  echo "ok";
}

$_REQUEST[qty] is posted with AJAX request ($.post). $_REQUEST[qty] is NOT empty and contains only number (1).

is_numeric() is not going to work, since it treats 1e4 as a number.

Answer 1

is_int will only return true if the variable is of integer type.
if you are trying to test if the variable contains a string which represents a number,
use:

is_numeric("1");

source: http://php.net/manual/en/function.is-int.php

EDIT:

use ctype_digit() to check for every character in the string if it’s a number to rule out “1e4”