Type casting and Comparison with Loose Operator “==”

Question

I have a problem baffling me terribly. I noticed this before but didn\'t give it any heed until today. I was trying to write my own check for integer strings. I know of

Answer 1

First of all in mathematices '=' is called transitive b/c (A=B and B=C => A=C) is valid.

This is not the case with PHPs "=="!

(int)$var1 == $var1

In that case PHP will cast 'string' to 0 - that's a convention.

Then ==-operator will implicitely have the second operand 'string' also be casted to integer -> as well 0.

That leads to true.