# C++ Program for Decimal to binary conversion

## Program for Decimal to binary conversion

Here we will discuss how to convert a decimal number into a binary number using C++ Programming language.

The concept of conversion is very simple.A decimal number can be converted to a binary number by using the repeated division-by-2 method i.e repeatedly divide the decimal number by 2 until no further divisions can be done and the remainder of each division will give us the binary number of the decimal.

Example:9

Step 1: 9/2, Remainder = 1, Quotient = 4

Step 2: 4/2, Remainder = 0, Quotient = 2

Step 3: 2/2, Remainder = 0, Quotient = 1

Step 4: 1/2, Remainder = 1, Quotient = 0

9 in decimal = 1001 in binary ### Working

Let’s see how the code works:

• User gives an input(decimal number).
• The input is stored in an int type variable say decimal.
• A function convert is called with decimal as a parameter.
• A loop is started
• The number is divided by 2 and the remainder is stored.

rem = n%2;

• The binary number is constructed using the remainder.

binary += rem*i;

• The loop will run until the number is not equal to 0.

while (n!=0)

• The output is printed.

### C++ Code

`//C++ Program//Decimal to binary conversion#include <iostream>#include <math.h>using namespace std;//function to convert decimal to binarylong convert(int n){    long binary = 0;    int i = 1;    //converting decimal to binary    while (n!=0)    {        int rem = n%2;        n /= 2;        binary += rem*i;        i *= 10;    }    return binary;}//main programint main(){    int decimal;    long binary;    cout << "Enter a decimal number: ";    //user input    cin >> decimal;    //calling function    binary = convert(decimal);    cout << decimal << " in decimal = " << binary << " in binary" << endl ;    return 0;}`

#### Output

`Enter a decimal number: 109109 in decimal = 1101101 in binary`