Let us consider the stmt
c= a + b

In operator overloading concept, value next to + operator i.e operand value' b' only passed to Overloading function that why in ur pgm 'b' value is copied to' param' operand......

operand ' a' value is passed automatically ,we no need to pass it........

As per ur stmt,
if we put a+b=c,
Which value get passed? Think over it?