Hamming Code in C

#include<stdio.h>

void main()
{
    int data[10];
    int dataatrec[10],c,c1,c2,c3,i;

    printf("Enter 4 bits of data one by one:\n");
    scanf("%d",&data[0]);
    scanf("%d",&data[1]);
    scanf("%d",&data[2]);
    scanf("%d",&data[4]);

    //Calculation of even parity
    data[6]=data[0]^data[2]^data[4];
    data[5]=data[0]^data[1]^data[4];
    data[3]=data[0]^data[1]^data[2];

    printf("\nEncoded data is\n");
    for(i=0; i<7; i++)
        printf("%d",data[i]);

    printf("\n\nEnter received data bits one by one\n");
    for(i=0; i<7; i++)
        scanf("%d",&dataatrec[i]);

    c1=dataatrec[6]^dataatrec[4]^dataatrec[2]^dataatrec[0];
    c2=dataatrec[5]^dataatrec[4]^dataatrec[1]^dataatrec[0];
    c3=dataatrec[3]^dataatrec[2]^dataatrec[1]^dataatrec[0];
    c=c3*4+c2*2+c1 ;

    if(c==0)
    {
        printf("\nNo error while transmission of data\n");
    }
    else
    {
        printf("\nError on position %d",c);

        printf("\nData sent : ");
        for(i=0; i<7; i++)
            printf("%d",data[i]);

        printf("\nData received : ");
        for(i=0; i<7; i++)
            printf("%d",dataatrec[i]);

        printf("\nCorrect message is\n");

        //if errorness bit is 0 we complement it else vice versa
        if(dataatrec[7-c]==0)
            dataatrec[7-c]=1;
        else
            dataatrec[7-c]=0;

        for (i=0; i<7; i++)
        {
            printf("%d",dataatrec[i]);
        }
    }
}


another hamming code...

#include <stdio.h>
#include <math.h>
int input[32];
int code[32];
int ham_calc(int,int);
void main()
{
    int n,i,p_n = 0,c_l,j,k;
    printf("Please enter the length of the Data Word: ");
    scanf("%d",&n);
    printf("Please enter the Data Word:\n");
    for(i=0;i<n;i++)
    {
        scanf("%d",&input[i]);
    }

    i=0;
    while(n>(int)pow(2,i)-(i+1))
    {
        p_n++;
        i++;
    }

    c_l = p_n + n;

    j=k=0;
    for(i=0;i<c_l;i++)
    {

        if(i==((int)pow(2,k)-1))
        {
            code[i]=0;
            k++;
        }
        else
        {
            code[i]=input[j];
            j++;
        }
    }
    for(i=0;i<p_n;i++)
    {
        int position = (int)pow(2,i);
        int value = ham_calc(position,c_l);
        code[position-1]=value;
    }
    printf("\nThe calculated Code Word is: ");
    for(i=0;i<c_l;i++)
        printf("%d",code[i]);
    printf("\n");
    printf("Please enter the received Code Word:\n");
    for(i=0;i<c_l;i++)
        scanf("%d",&code[i]);

    int error_pos = 0;
    for(i=0;i<p_n;i++)
    {
        int position = (int)pow(2,i);
        int value = ham_calc(position,c_l);
        if(value != 0)
            error_pos+=position;
    }
    if(error_pos == 1)
        printf("The received Code Word is correct.\n");
    else
        printf("Error at bit position: %d\n",error_pos);
}
int ham_calc(int position,int c_l)
{
    int count=0,i,j;
    i=position-1;
    while(i<c_l)
    {
        for(j=i;j<i+position;j++)
        {
            if(code[j] == 1)
                count++;
        }
        i=i+2*position;
    }
    if(count%2 == 0)
        return 0;
    else
        return 1;
}