C program for CRC

#include <stdio.h>
#include <conio.h>
#include <string.h>
void main()
{
int i,j,keylen,msglen;
char input[100], key[30],temp[30],quot[100],rem[30],key1[30];
clrscr();
printf("Enter Data: ");
gets(input);
printf("Enter Key: ");
gets(key);

keylen=strlen(key);
msglen=strlen(input);
strcpy(key1,key);

for (i=0;i<keylen-1;i++)
{
input[msglen+i]='0';
}

for (i=0;i<keylen;i++)
{
temp[i]=input[i];
}

for (i=0;i<msglen;i++)
{
quot[i]=temp[0];
if(quot[i]=='0')
{
for (j=0;j<keylen;j++)
key[j]='0';
}
else
{
   for (j=0;j<keylen;j++)
   key[j]=key1[j];
}
   for (j=keylen-1;j>0;j--)
   {
if(temp[j]==key[j])
rem[j-1]='0';

else
rem[j-1]='1';
   }


rem[keylen-1]=input[i+keylen];
strcpy(temp,rem);

}
strcpy(rem,temp);

printf("\nQuotient is ");

for (i=0;i<msglen;i++)
printf("%c",quot[i]);

printf("\nRemainder is ");

for (i=0;i<keylen-1;i++)
printf("%c",rem[i]);

printf("\nFinal data is: ");

for (i=0;i<msglen;i++)
printf("%c",input[i]);

for (i=0;i<keylen-1;i++)
printf("%c",rem[i]);

getch();
}


output

Enter Data: 11010011101100
Enter Key: 1011

Quotient is 11110001111100
Remainder is 100
Final data is: 11010011101100100