## Sunday, 13 October 2013

### 2's Complement of a Binary number

2's complement of binary no. is basicaly = 2^n -binary no.
where
n= no of digit before decimal.

#### Easy way to find out 2's complement of binary no :

=> Move from right to left of binary no. Untill fist 1 found .
=>Now change all no (1 by 0 && 0 by 1) before above first node .

#### Examples:

binary no =10010010              2's complement=01101110
binary no=0011001                 2's complement=1100111
binary no=10000                     2's complement= 10000
binary no=0001                       2's complement=0001

ALL highlighted  1 first occurence of 1

### C program :

`````` /*
To find 2s complement of a binary no
*/
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
main()
{
char bin[16];
int i,j,len;
printf("\n enter binary no :");
gets(bin); // taking input
/*...........chaeck input no is binaty or not............*/
len=strlen(bin);
for(i=0;i<len;i++)
{
if(bin[i]!='0' && bin[i]!='1')
{
printf("\n this is not a binary no");
exit(0);
}
}
/*..........end of check input............*/
/*............operation time.............*/
for(i=len-1;i>=0;i--) //to find position of first occurence of 1;
{
if(bin[i]=='1')
{
break;
}
}
for(j=i-1;j>=0;j--) // start loop again from j=first occurence of '1' -1;
{
if(bin[j]=='0') // replace volue o by 1
{
bin[j]='1';
}
else
bin[j]='0'; //replace 1 by 0
}
/*.............end of operation.........*/
printf("2's complement of given binaty no is :");
puts(bin);// to print string
}
``````