C program for binary subtraction using two's complement

1 Pseudocode:

1.      Start
2.      Ask user to enter two 8-bit numbers: num1, num2
3.      Begin Subtraction from LSB
4.      diff = num1[i] – num2[i]
5.      If difference of two bits < 0, num1[i-1] = num1[i-1] - 1
6.      diff = absolute(diff % 2)
7.      Repeat 5 through 7 until all bits are added
8.      Display diff
9.      End

2 Program:

#include <stdio.h>

#include <conio.h>

#include <math.h>

void main(){

            clrscr();

            int numa[8]={0},numb[8]={0},diff[8]={0};

            printf("\tSUBTRACTION USING TWO'S COMPLEMENT");

            printf("\nEnter two 8-bit binary numbers\n");

            printf("\nEnter first number: ");

            for(int i = 0; i<8; i++){

                        scanf("%d",&numa[i]);

            }

            printf("\nEnter second number: ");

            for(i = 0; i<8; i++){

                        scanf("%d",&numb[i]);

            }

            for(i = 7; i >= 0; i--){

                        diff[i] = numa[i] - numb[i];

                        if(diff[i] < 0){

                                    numa[i-1] = numa[i-1] - 1;

                        }

                        diff[i] = fabs(diff[i]%2);

            }

            printf("\nDifference is: ");

            for(i = 0; i<8; i++){

                        printf("%d",diff[i]);

            }

            getch();

}

©Dixit Bhatta 2013