how to convert decimal number to binary

[vmpstr]

I prefer looping over the number of bits and doing a check along the lines of

if ( num & (1 << curbit) )

If that is true, then bit curbit is set (the least significant bit being bit 0). This is very similar to what weaknessforcats said, except that one is

if ( (num >> curbit) & 1 )

:D

[YarrOfDoom]

I believe itoa() with base 2 would be kinda spoiling the fun.
That, and you don't learn anything from it.

[bcaparna]

Here,a much easier way to convert decimal in to base-2,8,16-

// this program converts the given decimal number into to the desired bases.
#include<iostream.h>
#include<conio.h>
#include<math.h>

void main()
{
 clrscr();
 int i, a[1], b, n;
 char ch;
 do
 {
  cout<<"Enter the Decimal Number to be converted: \n";
  cin>>n;
  if(n<0)
   {
     cout<<"Enter a Positive Number: \n";
   }
  else
   {
     cout<<"Enter the Base(2, 8 or 16): \n";
     cin>>b;
     if(b!=2 && b!=8 && b!=16)
            {
            cout<<"Invalid Base!"<<endl;
            }
            else
            {
            i=7;
                do
                {
                 a[i]=n%b;
                 n=n/b;
                 i--;
                }
                while(n>0);
                while(i>=0)
                {
                 a[i]=0;
                 i--;
                }
                for(i=0;i<=7;i++)
                {
                 if (a[i]==10)
                 cout<<"A";
                 if (a[i]==11)
                 cout<<"B";
                 if (a[i]==12)
                 cout<<"C";
                 if (a[i]==13)
                 cout<<"D";
                 if (a[i]==14)
                 cout<<"E";
                 if (a[i]==15)
                 cout<<"F";
                 else
                 cout<<"\t"<<a[i];
                }
            };
   }
  cout<<"\nDo you wish to convert another number? (y/n)"<<endl;
  cin>>ch;
 }
 while(ch!='n');
 getch();
}