PHP in_array ignoring leading zeros

Question

I have an array of 0845 numbers that is being searched via in_array for a specific numbers. For some reason, omitting the leading zero from the needle returns a false positive:

$numbers = array(
  '08451234567',
  '08452345678',
  '08453456789',
  '08454567890',
  ...
);

var_dump(in_array('08451234567', $numbers)); //(Boolean) TRUE - Right
var_dump(in_array('8451234567', $numbers)); //(Boolean) TRUE - Wrong

I have tried casting the values in the array as strings, but that did not work.

What is going on, and how do I fix it?

[edit]

Added quote around my needles

Answer 1

Use strict comparision

bool in_array ( mixed $needle , array $haystack [, bool $strict = FALSE ] )

Use

var_dump(in_array("08451234567", $numbers,true)); //(Boolean) true - OK
var_dump(in_array("8451234567", $numbers,true)); //(Boolean) false - OK

Why

var_dump(08451234567); // returns 0 because its octal 
var_dump((int) "08451234567"); // returns 8451234567
var_dump((float) "08451234567"); // returns  8451234567

Only

var_dump("08451234567" === "08451234567"); // returns true

See Live Demo

Answer 2

Quote it. 0123 without quotes is octal in PHP. It's in the docs

This has been answered in stackoverflow before.