Find 2's Complement for Given Binary Number Using C Language

Problem Statement

Given a binary number, you have to write a C program to find 2'c complements for given binary number.

Consider an example given below −

Example

The input is as follows:

Enter a binary number:10010001

The output is as follows:

1's complement of 10010001 is 01101110

2's complement of 10010001 is 01101111

Algorithm

Refer an algorithm to find 2’c complements for a given binary number.

Step 1 − Start.

Step 2 − Read the binary number at runtime.

Step 3 − Copy the binary number to strdp.

Step 4 − len: = strlen(str)

Step 5 − For i = 0 to len-1 do

     Step 5.1 − if str[i] == ‘1’ then

        Step 5.1.1 − str[i] == ‘0’

     Step 5.2 − Else

        Step 5.2.1 − str[i] == ‘1’

     Step 5.3 − i: = i+1

Step 6 − Mask: = 1

Step 7 − For i: = len-1 to 0 do

     Step 7.1 − if mask == 1 then

        Step 7.1.1 − if str[i] == ‘1’ then

           Step 7.1.1.1 − str[i]: = ‘0’

           Step 7.1.1.2 − mask: = 1

     Step 7.1.2 − else

        Step 7.1.2.1 − str[i]: = ‘1’

        Step 7.1.2.2 − mask: = 0

     Step 7.1.3 − End if

     Step 7.2 − End if

Step 8 − Print the 2’s complement.

Step 9 − Stop.

C program to find 2'c complements for a given binary number

Following is the C program to find 2’c complements for a given binary number −

 Live Demo

#include <string.h>
#include<stdio.h>
main(){
   char str[32],strdp[32];
   int mask,i;
   printf("Enter a binary number:");
   scanf("%s",str);
   strcpy(strdp,str);
   for(i=0;i<strlen(str);i++) /* computing 1's complement */{
      if(str[i]=='1')
         str[i]='0';
      else
         str[i]='1';
   }
   printf("1\'s complement of %s is %s
",strdp,str);
   mask=1;
   for(i=strlen(str)-1;i>=0;i--){
      if(mask==1){
         if(str[i]=='1'){
            str[i]='0';
            mask=1;
         }
         else{
            str[i]='1';
            mask=0;
         }
      }
   }
   printf("2\'s complement of %s is %s",strdp,str);
}

Output

When the above program is executed, it produces the following result −

Enter a binary number:11001110
1's complement of 11001110 is 00110001
2's complement of 11001110 is 00110010