1’s and 2’s complement of a Binary Number?

Binary Number is expressed in base 2. It uses only two digits ‘0’ and ‘1’. Each digit in a binary number is a bit.

Sample binary Number − 0100010111

1’s Complement

One's complement of a binary number is obtained by reversing the digits of the binary number i.e. transforming 1 with 0 and 0 with 1.

Example

1’s Complement of 101100 = 010011

2’s Complement

Two’s complement of a binary number is obtained by adding one to the one’s complement of a binary number i.e. 1’s complement + 1.

Example

2’s complement of 101101 is 010011.

Example Code

Code to find One’s and two’s complement −

#include <iostream>
#include<string.h>
using namespace std;
int main() {
   char binary[10] = "01001011";
   cout<<“Binary number is ”<<binary;
   //once complement....
   int length = strlen(binary);
   for(int i=0;i<length;i++) {
      if(binary[i] == '0') {
         binary[i]= '1';
      } else
         binary[i] = '0';
   }
   cout<<“One’s Complement is ”<<binary<<endl;
   // cout<<binary[length-1];
   for(int i = length-1; i>=0; i--) {
      // cout<<binary[i];
      if(binary[i] == '0') {
         binary[i] = '1';
         //cout<<binary[i];
         break;
      } else {
         binary[i] = '0';
      }
   }
   cout<<“Two’s complement is ”<<binary;
   return 0;
}

Output

Binary number is 01001011
One’s complement is 10110100
Two’s complement is 10110101