ImportantC++ code for decimal to binary number

/*C++ code for decimal to binary number*/

  #include<iostream>

using namespace std;

int main()

{

    int decimalNum, binaryNum[20], i=0;

    cout<<"Enter the Decimal Number: ";

    cin>>decimalNum;

    while(decimalNum!=0)

    {

        binaryNum[i] = decimalNum%2;

        i++;

        decimalNum = decimalNum/2;

    }

    cout<<"\nBinary Value: ";

    for(i=(i-1); i>=0; i--)

        cout<<binaryNum[i];

    cout<<endl;

    return 0;

}

****************Important***********

Initial value, i=0

When user enters a decimal

 number say 105, then it

 gets stored in decimalNum. 

So decimalNum=105

Now the condition decimalNum!=0

 (of while loop) gets evaluated

The condition decimalNum!=0 

or 

105!=0 evalutes to be true, 

therefore program flow goes 

inside the loop

And decimalNum%2 or 105%2

 or 

1 gets intialized to binaryNum[i]

 or

 binaryNum[0]. So, binaryNum[0]=1

The value of i gets incremented.

 Now i=1

And decimalNum/2 or 52 gets

 initialized to decimalNum.

 Now decimalNum=52

Program flow goes back and 

evaluates the condition of

 while loop again with new 

value of decimalNum (52)

Because again the

 condition evaluates to be true,

 therefore program flow 

again goes inside the loop

And again, decimalNum%2 

or 

52%2 or 0 gets initialized 

to binaryNum[i]

 or

 binaryNum[1]. So binaryNum[1]=0

Again the value of i gets

 incremented.

 So i=2

And then decimalNum/2 or

 52/2 or 26 gets initialized to

 decimalNum. So decimalNum=26

Process the same, from step no.8 

to 12 with new value of 

decimalNum and i

On continuing the process

 in similar way until

 the condition of while 

loop evaluates to be false,

 we will get the values of

 binaryNum[] as:

binaryNum[0]=1

binaryNum[1]=0

binaryNum[2]=0

binaryNum[3]=1

binaryNum[4]=0

binaryNum[5]=1

binaryNum[6]=1

When the value of decimalNum

 becomes equal to 0,

 then the condition decimalNum!=0

 or 

0!=0 evaluates to be false,

 therefore the evaluation of

 while loop gets ended. 

And using for loop, 

the value of binaryNum[] 

gets printed

The value of binaryNum[] 

gets printed from its last 

to 0th index

That will be, 1101001

*********************************

#include<iostream>

using namespace std;

int main()

{

    int decnum, binnum=0, i=1, rem;

    cout<<"Enter any decimal Number: ";

    cin>>decnum;

    while(decnum!=0)

    {

        rem = decnum%2;

        binnum = binnum + (rem*i);

        

        

       

        

         i = i*10;

        decnum = decnum/2;

    }

    cout<<"\n binary Value = "<<binnum;

   

    return 0;

}