2's complement in C

Hai,

1) In one book, I have read that in C Programming, to store negative numbers , 2's complements are used. Why is it like that ? Is there any advantage to use 2's complement?(Positive numbers will be stored in ordinary binary format, Am I correct?)

2) How can I represent (-128) in 2's complement form?

Advance thanks for your responses.

-Kokila

Quote:

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Originally posted by Kokila
Hai,


2) How can I represent (-128) in 2's complement form?

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Code:

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int foo;

foo = -128;

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Quote:

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Originally posted by Kokila
Hai,

1) In one book, I have read that in C Programming, to store negative numbers , 2's complements are used. Why is it like that ? Is there any advantage to use 2's complement?(Positive numbers will be stored in ordinary binary format, Am I correct?)

2) How can I represent (-128) in 2's complement form?

Advance thanks for your responses.

-Kokila

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For signed values, the most significant bit is set to 1 for negative values....on positives, it is set to 0

-128 = 1111 1111 1000 0000

+128 = 0000 0000 1000 0000

Whether C uses 2's compliment is specific to the machine, not to C. C covers up details like this so that if you write conforming programs it won't matter if the machine is 2's compliment or not.

Bebop