Difference between casting to a class and to an interface

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From: yufufi (yufufi_at_ttnet.net.tr)
Date: 07/04/04 

Date: Sun, 4 Jul 2004 16:17:48 +0300

lets say we have a 'shape' class which doesn't implement IComparable
interface..

compiler doesn't give you error for the lines below..

shape b= new shape();
IComparable h;
h=(IComparable)b;

but it complains for the following lines
shape b= new shape();
int a;
a=(int)b;

error is Cannot convert type 'shape' to 'int'

is there difference between casting to a class and casting to an interface
?? what does the compiler checks when it is casting to an interface (or does
it check anything ?)

Thanx a lot,

yufufi

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