Possible Duplicate:
How do the equality (== double equals) and identity (=== triple equals) comparison operators differ?
Why this
var_dump(0 == "string");
outputs this
bool(true)
Isn’t the context of == operator supposed to convert 0 into FALSE and "string" into TRUE according to this set of rules?
is doing a numeric (integer) comparison
0 is an integer, so “string” is converted to an integer to do the comparison, and equates to an integer value of 0, so 0 == 0 is true
Se the comparison with various types table in the PHP documentation for details