Thanks for the code Kedar. Is it tested one?

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]);

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 && dataatrec[6]==data[6] && dataatrec[5]==data[5] && dataatrec[3]==data[3] ) {
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(dataatrec[7-c]==0)
dataatrec[7-c]=1;
else
dataatrec[7-c]=0;

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