returning zero when converting string to integer in php

Question

when I want to convert a numeric string variable into integer in php, the return value is zero. I used all ways to convert it! such as:(int), (integer), intval(), settype(), eval(), etc. all of them return zero!

var_dump($myVariable) prints the following:

string(4) "۲۹"

Answer 1

Other common error is trying to cast a string variable that contains numbers but starts with zero, i.e.:

string(5) " 358"

To solve this, I used a filter_var sanitizing number INT doing this:

$myVariable = filter_var($myVariable, FILTER_SANITIZE_NUMBER_INT);