Find the 2's complement of a given binary number using C

Consider the example given below -

Example

Enter as follows:

Enter the binary number : 10010001

The output is as follows:

1 The complement of 10010001 is 01101110

2 The complement of 10010001 is 01101111

Algorithm

Refer to an algorithm to find the 2'c complement of a given binary number.

Step 1 - Get Started.

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 execute

Step 5.1 - If str[i] == '1' then

Step 5.1.1 - str[i] == '0'

Step 5.2 - Otherwise

Step 5.2.1 - str[i ] == '1'

Step 5.3 - i: = i 1

Step 5.3 - i: = i 1

p>

Step 6 - Mask Code: = 1

Step 7 - For i: = len-1 to 0 execute

Step 7.1 - If mask == 1 then p>

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 2's complement.

Step 9 - Stop.

Program

The following is a C program to find the 2'c complement of a given binary number -

Live Demonstration

#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&#39;s complement */{
      if(str[i]==&#39;1&#39;)
         str[i]=&#39;0&#39;;
      else
         str[i]=&#39;1&#39;;
   }
   printf("1\&#39;s complement of %s is %s</p><p>",strdp,str);
   mask=1;
   for(i=strlen(str)-1;i>=0;i--){
      if(mask==1){
         if(str[i]==&#39;1&#39;){
            str[i]=&#39;0&#39;;
            mask=1;
         }
         else{
            str[i]=&#39;1&#39;;
            mask=0;
         }
      }
   }
   printf("2\&#39;s complement of %s is %s",strdp,str);
}

Output

When the above program is executed, the following results are produced-

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

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