Cyclic Redundancy Check (CRC) Program in C++

// SIMULATE CYCLIC REDUNDANCY CHECK (CRC)
#include<iostream.h>
#include<conio.h>
#include<math.h>
#include<stdlib.h>
#include<graphics.h>
#include<DOS.h>
int digitinbin(int number)
{  int i=0;
  int n=number;
  while(n!=0)
    { n=n/2;
      i++;
    }
   return i;
}
int bintodec(int *a,int d)
{  int num=0;
   for(int i=0;i<d;i++)
    { if(a[i]==1)
       num=num+pow(2,i);
    }
  return num;
}
int* dectobin(int n)
{ int *A=new int[32];
  int i=0;
  int num=n;
  while(num!=0)
    { A[i]=num%2;
      num=num/2;
      i++;
    }
  return A;
}

int sender(int mess,int poly)
{ int k=0,num1;
  int d1=digitinbin(poly);
  mess=mess*pow(2,d1-1);
  int d2=digitinbin(mess);
  int *B=dectobin(mess);
  int counter=0;
  int times=d2-d1+1;
  int *temp=new int[d1];
  int a=pow(2,d1-1);
  while(counter<times)
   { int j=0;
     if(counter==0)
      {
     for(int i=times-counter-1;i<d2-counter;i++)
      {  temp[j]=B[i];
  j++;
      }
      num1=bintodec(temp,j);
      }
      int num2=poly;
      if(counter!=0)
       num1=k;
     if(num1>=a)
       k=num1^num2;
     else
       k=num1;

     if(d2-d1-counter-1>=0)
     {
     if(B[d2-d1-counter-1]==1)
      k=k*2+1;
     else
      k=k*2;
     }
   counter++;
    }
   return (k^mess);
}
void receiver(int mess,int poly)
{ int k=0,num1;
  int d1=digitinbin(poly);
  int d2=digitinbin(mess);
  int *B=dectobin(mess);
  int counter=0;
  int times=d2-d1+1;
  int *temp=new int[d1];
  int a=pow(2,d1-1);
  while(counter<times)
   { int j=0;
     if(counter==0)
      {
     for(int i=times-counter-1;i<d2-counter;i++)
      {  temp[j]=B[i];
  j++;
      }
      num1=bintodec(temp,j);
      }
      int num2=poly;
      if(counter!=0)
       num1=k;
     if(num1>=a)
       k=num1^num2;
     else
       k=num1;

     if(d2-d1-counter-1>=0)
     {
     if(B[d2-d1-counter-1]==1)
      k=k*2+1;
     else
      k=k*2;
     }
   counter++;
    }
  if(k==0)
    cout<<"MESSAGE TRANSMITTED SUCCESSFULLY\n"<<endl;
  else
    cout<<"ERROR IN TRANSMISSION\n"<<endl;

}
void main()
{ clrscr();
  int message,genpoly,ch=1;
  cout<<"enter the number to be transmitted"<<endl;
  cin>>message;
  cout<<"Enter the generator polynomial number"<<endl;
  cin>>genpoly;
  int gp=sender(message,genpoly);

  while(ch==1 || ch==2)
  {
  cout<<"MENU"<<endl;
  cout<<"1-SUCCESSFUL TRANSMISSION"<<endl;
  cout<<"2-ERROR IN TRANSMISSION"<<endl;
  cout<<"PRESS ANY OTHER KEY TO EXIT"<<endl;
  cout<<"Enter your choice"<<endl;
  cin>>ch;
   if(ch==1)
  { cout<<"TRANSMITTING MESSAGE .......\n"<<endl;
    delay(5000);
    receiver(gp,genpoly);
    int *B=dectobin(message);
    int dig=digitinbin(message);
    cout<<"The transmitted message is ";
      for(int i=dig-1;i>=0;i--)
 cout<<B[i];
    cout<<"\n"<<endl;
  }
   else
   if(ch==2)
  {  cout<<"TRANSMITTING MESSAGE .......\n"<<endl;
    delay(5000);
    receiver(gp+1,genpoly);
     cout<<endl;
   }
}

 cout<<"PROGRAM ENDS"<<endl;
getch();
}

/*     OUTPUT

enter the number to be transmitted
729
Enter the generator polynomial number
19
MENU
1-SUCCESSFUL TRANSMISSION
2-ERROR IN TRANSMISSION
PRESS ANY OTHER KEY TO EXIT
Enter your choice
1
TRANSMITTING MESSAGE .......

MESSAGE TRANSMITTED SUCCESSFULLY

The transmitted message is 1011011001

MENU
1-SUCCESSFUL TRANSMISSION
2-ERROR IN TRANSMISSION
PRESS ANY OTHER KEY TO EXIT
Enter your choice
2
TRANSMITTING MESSAGE .......

ERROR IN TRANSMISSION


MENU
1-SUCCESSFUL TRANSMISSION
2-ERROR IN TRANSMISSION
PRESS ANY OTHER KEY TO EXIT
Enter your choice
4
PROGRAM ENDS

*/