C program to find 2’s complement of a binary number

In this article we will learn to implement a C program to find 2’s complement of a binary number. A C program is provided below which reads a binary number and prints its 2’s complement.

Program is as follows:

//C program to find the 2's complement of a given binary number
#include<stdio.h>
#include<conio.h>
void main()
{
	int n, a[10], i;
	bool flag = false;
	printf("Enter number of binary numbers: ");
	scanf("%d",&n);
	printf("Enter %d binary numbers:", n);
	for(i=0;i<n;i++)
	{
		scanf("%d", &a[i]);
	}
	//Scanning from right side i.e from last entered binary number
	for(i=n-1;i>=0;i--)
	{
		if(a[i]==1 && flag==false)
		{
			flag = true;
			continue;
		}
		if(a[i]==0 && flag==false)
		{
			continue;
		}
		if(a[i]==1)
			a[i]=0;
		else
			a[i]=1;
	}
	printf("2's complement is: ");
	for(i=0;i<n;i++)
	{
		printf("%d ",a[i]);
	}
	getch();
}

Input and output for the above program is as follows:

Enter number of binary numbers: 6
Enter 6 binary numbers:1 0 0 0 1 1
2's complement is: 0 1 1 1 0 1

Suryateja Pericherla

Suryateja Pericherla, at present is a Research Scholar (full-time Ph.D.) in the Dept. of Computer Science & Systems Engineering at Andhra University, Visakhapatnam. Previously worked as an Associate Professor in the Dept. of CSE at Vishnu Institute of Technology, India.

He has 11+ years of teaching experience and is an individual researcher whose research interests are Cloud Computing, Internet of Things, Computer Security, Network Security and Blockchain.

He is a member of professional societies like IEEE, ACM, CSI and ISCA. He published several research papers which are indexed by SCIE, WoS, Scopus, Springer and others.