test.c

#include <stdio.h>
#include <string>


int main()
{
	int no=0,i,cnt=0,bcnt=0,alt=1;
	char hamm[20];
	string data;
	hamm[0]=NULL;
	printf("Enter data:");
	scanf("%c",&data);

	for(i=1;i<=data.length()+4;i++)
	{

		if(i==1 || i==2 || i==4 ||i==8)
			hamm[i-1]=' ';
		else
		{
			hamm[i-1]=data[cnt];
			cnt++;
		}
	}
	hamm[data.length()+4]='\0';
	
	int n=0;alt=1;
	while(alt<=8)
	{
		bcnt=0;
		n=alt-1;
		for(i=n;i<data.length()+4;)
		{
			if(alt%2==1)					// for 1st position i.e. odd position
			{
				if(hamm[i]=='1')
					bcnt+=1;
				else if(hamm[i]=='0')
					bcnt+=0;
				i+=(alt*2);
			}
			else if(alt%2==0)				// for other positions i.e. even positions
			{
				if((i/alt)%2==0 && i%2==1)		//((odd/2)%alt==0 || ((even-1)/2)%alt==0)
				{
					if(hamm[i]=='1')
						bcnt+=1;
					else if(hamm[i]=='0')
						bcnt+=0;
				}
				else if(((i-1)/alt)%2==0 && i%2==0)
				{
					if(hamm[i]=='0')
						bcnt+=0;
					else if(hamm[i]=='1')
						bcnt+=1;
				}
				i++;
			}
		}
		//cout<<bcnt<<endl;
		if(bcnt%2==0 && alt%2==0)
			hamm[alt-1]='0';
		else if(bcnt%2==1 && alt%2==0)
			hamm[alt-1]='1';
		else if(bcnt%2==0 && alt%2==1)
			hamm[0]='0';
		else if(bcnt%2==1 && alt%2==1)
			hamm[0]='1';

		cout<<endl<<hamm<<endl;
		alt*=2;
	}
	printf("The Hamming code of %s is %c",data,hamm);
	return 0;
}