Explicit Type Casting

[mamidi venkat]

Hi All,

I have a doubt in explicit typecasting .How internally it happens can any body explain briefly (In case of Byte or int)how -128 has come in the output


public class test{
public static void main(String[] args)
{
byte d=(byte)128;
System.out.println(d);
}
}
o/p -128

[Deepak Jain]

Its simple.
Size of byte is 8 bits, So the range of values it can take
is -2x7 to + 2x7-1 which is (-128 to 127) . If you assign any value out of this range it will cycle through the above range [bit calculation]. Since you have assigned 128 which is excatly next number to 127 and so the value thats stored in byte variable is -128.
Hope this answers your question.
Thanks
Deepak

[Priyam Srivastava]

Refer pag 186 K&B Ch-3 Indian Sub-Continent Edition

[Amit Mahajan]

Hey it's simple

128 in bits is 1000 0000

A byte has it's 8th bit as the sign bit.
Hence 1000 0000 , a byte will interpret as negative number and
the no. will be calculated using 2's complement.

Which means 1000 0000 --> 0111 1111
+ 1
----------
1000 0000

O/P -128

[Burkhard Hassel]

Hi
Amit M

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Regards,
Bu.