W.A.P to implement Cyclic Redundancy Check method.

#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
#define DIVLENGTH 4
#define DIV 1101

int rmainB (long int x,int y);
char *binadd(int,int);
char *dec2bin(int rem);
int mPow(int x,int y);
int bin2dec(long int x);

void main()
{
char *str,*crc,*tmp;
int i=0,n;
clrscr();
printf("\n\n\t Enter Info: ");
scanf("%s",str);
while(str[i]!='\0')
i++;
for(n=0;n<DIVLENGTH-1;n++)
str[i+n]='0';
str[i+n]='\0';
crc=dec2bin(rmainB(atol(str),DIV));
n=strlen(crc);
str=binadd(bin2dec(atol(str)),bin2dec(atol(crc)));
printf("\n\n\t Sender Send. \n\n\t Data : %s\n\n",str);
printf("\n\n\t Divisior : %d ", DIV);
printf("\n\n\t Waiting For Receiver's Response..");
for(i=0;i<6;i++)
{
printf(".");
delay(1000);
}
if(rmainB(atol(str),DIV)==0)
printf("\n\tAccepted..");
else
printf("\n\tRejected..");
printf("\n\n\tPress Any Key To Continue...");
getch();
}

int mPow(int x,int y)
{
int ret=1,i;
for(i=1;i<=y;i++)
ret*=x;
return ret;
}

int bin2dec(long int x)
{
int i=0,bx=0;
while(x > 0)
{
bx+=mPow(2,1)*(x % 10);
i++;
x=x/10;
}
return bx;
}

char *dec2bin(int rem)
{
int i=0;
char *tmp;
while(rem > 0)
{
if(rem % 2 == 0)
tmp[i]='0';
else
tmp[i]='1';
i++;
rem=rem/2;
}
if(i==0)
{
tmp[i++]='0';
tmp[i]='\0';
}
else
{
tmp[i]='\0';
tmp=strrev(tmp);
}
return tmp;
}

char *binadd(int x, int y)
{
char *tmp;
x=x+y;
tmp=dec2bin(x);
return tmp;
}

int rmainB(long int x, int y)
{
int rem,bx=0,by=0;
bx=bin2dec(x);
by=bin2dec(y);
rem= bx % by;
return rem;
}