# Find 2’c complements for given binary number using C language

CServer Side ProgrammingProgramming

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.

## Program

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];
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\n",strdp,str);
for(i=strlen(str)-1;i>=0;i--){
if(str[i]=='1'){
str[i]='0';
}
else{
str[i]='1';
}
}
}
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
Updated on 01-Sep-2021 09:00:14