Program for Decimal to Binary Conversion

2.2

Given a decimal number as input, we need to write a program to convert the given decimal number into equivalent binary number.

Examples:

Input : 7
Output : 111

Input : 10
Output : 1010

Input: 33
Output: 100001

Algorithm:

  1. Store the remainder when the number is divided by 2 in an array.
  2. Divide the number by 2
  3. Repeat the above two steps until the number is greater than zero.
  4. Print the array in reverse order now.

For Example:
If the binary number is 10.
Step 1: Remainder when 10 is divided by 2 is zero. Therefore, arr[0] = 0.
Step 2: Divide 10 by 2. New number is 10/2 = 5.
Step 3: Remainder when 5 is divided by 2 is 1. Therefore, arr[1] = 1.
Step 4: Divide 5 by 2. New number is 5/2 = 2.
Step 5: Remainder when 2 is divided by 2 is zero. Therefore, arr[2] = 0.
Step 6: Divide 2 by 2. New number is 2/2 = 1.
Step 7: Remainder when 1 is divided by 2 is 1. Therefore, arr[3] = 1.
Step 8: Divide 1 by 2. New number is 1/2 = 0.
Step 9: Since number becomes = 0. Print the array in reverse order. Therefore the equivalent binary number is 1010.

Below diagram shows an example of converting the decimal number 17 to equivalent binary number.

Below is the implementation of above idea.

C/C++

// C++ program to convert a decimal
// number to binary number

#include <iostream>
using namespace std;

// function to convert decimal to binary
void decToBinary(int n)
{
    // array to store binary number
    int binaryNum[1000];

    // counter for binary array
    int i = 0;
    while (n > 0) {

        // storing remainder in binary array
        binaryNum[i] = n % 2;
        n = n / 2;
        i++;
    }

    // printing binary array in reverse order
    for (int j = i - 1; j >= 0; j--)
        cout << binaryNum[j];
}

// Driver program to test above function
int main()
{
    int n = 17;
    decToBinary(n);
    return 0;
}

Java

// Java program to convert a decimal
// number to binary number
import java.io.*;

class GFG 
{
    // function to convert decimal to binary
    static void decToBinary(int n)
    {
        // array to store binary number
        int[] binaryNum = new int[1000];
 
        // counter for binary array
        int i = 0;
        while (n > 0) 
        {
            // storing remainder in binary array
            binaryNum[i] = n % 2;
            n = n / 2;
            i++;
        }
 
        // printing binary array in reverse order
        for (int j = i - 1; j >= 0; j--)
            System.out.print(binaryNum[j]);
    }
    
    // driver program
    public static void main (String[] args) 
    {
        int n = 17;
        decToBinary(n);
    }
}

// Contributed by Pramod Kumar


Output:

10001

This article is contributed by Harsh Agarwal. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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