decimal number into binary number system

#include
#include
#include

void dec_bin(long int num)   // Function Definition
{
long int rem[50],i=0,length=0;
while(num>0)
 {
 rem[i]=num%2;
 num=num/2;
 i++;
 length++;
 }
printf("\nBinary number : ");
     for(i=length-1;i>=0;i--)
             printf("%ld",rem[i]);
}
//================================================
void main()
{
long int num;
clrscr();
 
 printf("Enter the decimal number : ");
 scanf("%ld",&num);

    dec_bin(num);   // Calling function

 getch();
}