how to represent out of range number in binary?

In 2 complements I read from wikipedia, the range is from -128 to 127. So I wonder how do we repres开发者_如何转开发ent 128 in 2 complement as it is out of range above?

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You use more bits.

The range -128 to +127 is 256 unique values, which is 8 bits. If you need a larger range, you need more bits.

There is nothing restricting 2s-complement numbers to 8-bit values. For instance, a 16-bit 2s-complement number ranges from -32768 to +32767.

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8-bit gives you the range: [-2^7 , 2^7-1] = [-128,127]

In general, 2's complement using n-bit can represent numbers in the range:

-2^(n-1) to +2^(n-1)-1

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You can't, if you've only got 8 bits to work with. Unless you're willing to treat treat1000 0000as both −128 and +128.