Why does PHP convert String to Integer?

Question

I would like to know on what condition PHP decides when to convert from String to Integer and the other way around

Example:

$key = 0;
$test = \'test         


        

Answer 1

It converts strings to numbers when either operand is a number. The manual puts it cryptically like this:

http://php.net/manual/en/language.operators.comparison.php

For various types, comparison is done according to the following table (in order).

Operand 1           Operand 2

null or string      string              Convert NULL to "", numerical
                                        or lexical comparison
...

string, resource    string, resource    Translate strings and resources
or number           or number           to numbers, usual math

Note that the "in order" part is important when reading this table.