two's complement

English

Noun

two's complement (plural two's complements)

1. (computing) The number obtained by complementing every bit of a given number and adding one. A number and its complement add to 2ⁿ, where n is the word size of the machine.

   The two's complement of 0xAAAA is 0x5556 on a 16-bit machine, and 0xFFFF5556 on a 32-bit machine.

2. (computing) The convention by which bit patterns with high bit 0 represent positive numbers from 0 to $2^{n-1}-1$ directly, while bit patterns with high bit 1 represent negative numbers from −1 to $-2^{n-1}$, n being the word size of the machine, and the numeric complement of a number is its two's complement.

   Nearly all modern computers use two's complement for integer arithmetic.

Related terms

• complement
• radix complement
• numeric complement
• ones' complement

Translations

Translations

• Finnish: kahden komplementti
• Hungarian: kettes komplemens
• Icelandic: tvíundafyllitala f, tvíundafylling f
• Portuguese: complemento de dois m

See also

• signed magnitude