Program for Decimal to Binary Conversion
Given a decimal number as input, we need to write a program to convert the given decimal number into an equivalent binary number.
Input : 7
Output : 111
Input : 10
Output : 1010
Input: 33
Output: 100001
Brute force Approach
For Example:Â
If the decimal number is 10.Â
Step 1: Remainder when 10 is divided by 2 is zero. Therefore, arr[0] = 0.Â
Step 2: Divide 10 by 2. New number is 10/2 = 5.Â
Step 3: Remainder when 5 is divided by 2 is 1. Therefore, arr[1] = 1.Â
Step 4: Divide 5 by 2. New number is 5/2 = 2.Â
Step 5: Remainder when 2 is divided by 2 is zero. Therefore, arr[2] = 0.Â
Step 6: Divide 2 by 2. New number is 2/2 = 1.Â
Step 7: Remainder when 1 is divided by 2 is 1. Therefore, arr[3] = 1.Â
Step 8: Divide 1 by 2. New number is 1/2 = 0.Â
Step 9: Since number becomes = 0. Print the array in reverse order. Therefore the equivalent binary number is 1010.
The below diagram shows an example of converting the decimal number 17 to an equivalent binary number.Â
Below is the implementation of the above idea. Â
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[32];
// 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;
}
C
// C Code to convert Decimal number into Binary
#include <stdio.h>
void decToBinary(int n)
{
// array to store binary number
int binaryNum[32];
// 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--)
printf("%d", 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[32];
// 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
C#
// C# program to convert a decimal
// number to binary number
using System;
public class GFG {
// function to convert decimal
// to binary
static void decToBinary(int n)
{
// array to store binary number
int[] binaryNum = new int[32];
// 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--)
Console.Write(binaryNum[j]);
}
// Driver Code
public static void Main()
{
int n = 17;
decToBinary(n);
}
}
// This code is contributed by Sam007.
Javascript
<script>
// Javascript program to convert a decimal
// number to binary number
// function to convert decimal to binary
function decToBinary(n)
{
// array to store binary number
let binaryNum = new Array(32);
// counter for binary array
let i = 0;
while (n > 0) {
// storing remainder in binary array
binaryNum[i] = n % 2;
n = Math.floor(n / 2);
i++;
}
// printing binary array in reverse order
for (let j = i - 1; j >= 0; j--)
document.write(binaryNum[j]);
}
// Driver program to test above function
let n = 17;
decToBinary(n);
// This code is contributed by Mayank Tyagi
</script>
PHP
<?php
// PHP program to convert a decimal
// number to binary number
// function to convert
// decimal to binary
function decToBinary($n)
{
// array to store
// binary number
$binaryNum;
// counter for binary array
$i = 0;
while ($n > 0)
{
// storing remainder
// in binary array
$binaryNum[$i] = $n % 2;
$n = (int)($n / 2);
$i++;
}
// printing binary array
// in reverse order
for ($j = $i - 1; $j >= 0; $j--)
echo $binaryNum[$j];
}
// Driver Code
$n = 17;
decToBinary($n);
// This code is contributed by m_kit
?>
Python3
# Python3 program to convert a
# decimal number to binary number
# function to convert
# decimal to binary
def decToBinary(n):
# array to store
# binary number
binaryNum = [0] * n
# counter for binary array
i = 0;
while (n > 0):
# storing remainder
# in binary array
binaryNum[i] = n % 2
n = int(n / 2)
i += 1
# printing binary array
# in reverse order
for j in range(i - 1, -1, -1):
print(binaryNum[j], end = "")
# Driver Code
n = 17
decToBinary(n)
# This code is contributed by mits
Time complexity: O(logn)Â & Auxiliary Space: O(1)Â
We can use bitwise operators to do the above job. Note that bitwise operators work faster than arithmetic operators used above.
C++
// CPP program to Decimal to binary conversion
// using bitwise operator
// Size of an integer is assumed to be 32 bits
#include <iostream>
using namespace std;
// Function that convert Decimal to binary
void decToBinary(int n)
{
// Size of an integer is assumed to be 32 bits
for (int i = 31; i >= 0; i--) {
int k = n >> i;
if (k & 1)
cout << "1";
else
cout << "0";
}
}
// driver code
int main()
{
int n = 32;
decToBinary(n);
}
C
// C language to convert Decimal to binary number
// using bitwise operator
// Size of an integer is assumed to be 32 bits
#include <stdio.h>
// Function that convert Decimal to binary
int decToBinary(int n)
{
// Size of an integer is assumed to be 32 bits
for (int i = 31; i >= 0; i--) {
int k = n >> i; // right shift
if (k & 1) // helps us know the state of first bit
printf("1");
else printf("0");
}
}
// driver code
int main()
{
int n = 32;
decToBinary(n);
}
Java
// Java program to Decimal to binary conversion
// using bitwise operator
// Size of an integer is assumed to be 32 bits
class gfg {
// Function that convert Decimal to binary
public void decToBinary(int n)
{
// Size of an integer is assumed to be 32 bits
for (int i = 31; i >= 0; i--) {
int k = n >> i;
if ((k & 1) > 0)
System.out.print("1");
else
System.out.print("0");
}
}
}
class geek {
// driver code
public static void main(String[] args)
{
gfg g = new gfg();
int n = 32;
g.decToBinary(n);
}
}
// This code is contributed by mits
C#
// C# program to Decimal to binary conversion
// using bitwise operator
// Size of an integer is assumed to be 32 bits
using System;
class gfg {
// Function that convert Decimal to binary
public void decToBinary(int n)
{
// Size of an integer is assumed to be 32 bits
for (int i = 31; i >= 0; i--) {
int k = n >> i;
if ((k & 1) > 0)
Console.Write("1");
else
Console.Write("0");
}
}
}
class geek {
// driver code
public static int Main()
{
gfg g = new gfg();
int n = 32;
g.decToBinary(n);
return 0;
}
}
Javascript
<script>
// javascript program to Decimal to binary conversion
// using bitwise operator
// Size of an integer is assumed to be 32 bits
// Function that convert Decimal to binary
function decToBinary(n)
{
// Size of an integer is assumed to be 32 bits
for (i = 31; i >= 0; i--) {
var k = n >> i;
if ((k & 1) > 0)
document.write("1");
else
document.write("0");
}
}
// driver code
var n = 32;
decToBinary(n);
// This code contributed by Princi Singh
</script>
PHP
<?php
// PHP program to Decimal to binary conversion
// using bitwise operator
// Size of an integer is assumed
// to be 32 bits
// Function that convert Decimal to binary
function decToBinary($n)
{
// Size of an integer is
// assumed to be 32 bits
for ( $i = 31; $i >= 0; $i--)
{
$k = $n >> $i;
if ($k & 1)
echo "1";
else
echo "0";
}
}
// Driver Code
$n = 32;
decToBinary($n);
// This code is contributed by aj_36
?>
Python3
# Python3 program to Decimal
# to binary conversion using
# bitwise operator
# Size of an integer is
# assumed to be 32 bits
# Function that convert
# Decimal to binary
def decToBinary(n):
# Size of an integer is
# assumed to be 32 bits
for i in range(31, -1, -1):
k = n >> i
if (k & 1):
print("1", end="")
else:
print("0", end="")
# Driver Code
n = 32
decToBinary(n)
# This code is contributed by mits
Output00000000000000000000000000100000
Time complexity: O(1)Â
loop iterates constant(32) number of times everytime even for small numberÂ
Auxiliary Space: O(1)
Efficient Approach
It’s another efficient approach to converting Decimal to binary using the right shift(>>) and And(&) operator. Here we’ll use only Binary Operators which usually are very fast in computation.
C++
#include <bits/stdc++.h>
using namespace std;
string DecimalToBinary(int num)
{
string str;
while(num){
if(num & 1) // 1
str+='1';
else // 0
str+='0';
num>>=1; // Right Shift by 1
}
return str;
}
void reverse(string str)
{
for(int i=str.size()-1 ; i>=0 ; i--)
cout<< str[i];
}
int main() {
int num = 59;
cout<< "Binary of num 59 is: ";
reverse( DecimalToBinary(num) );
return 0;
}
Java
// Java program to implement the
// above approach
import java.io.*;
class GFG
{
// the converts decimal to binary base
static String DecimalToBinary(int num)
{
String str = "";
while (num > 0) {
if ((num & 1) == 1) // 1
str += '1';
else // 0
str += '0';
num >>= 1; // Right Shift by 1
}
return str;
}
// reverse the string
static void reverse(String str)
{
for (int i = str.length() - 1; i >= 0; i--)
System.out.print(str.charAt(i));
}
public static void main(String[] args)
{
int num = 59;
System.out.print("Binary of num 59 is: ");
reverse(DecimalToBinary(num));
}
}
// This code is contributed by phasing17
C#
// C# program to implement the
// above approach
using System;
public class GFG
{
// this converts decimal to binary base
public static string DecimalToBinary(int num)
{
string str = "";
while (num > 0) {
if ((num & 1) == 1) // 1
str += '1';
else // 0
str += '0';
num >>= 1; // Right Shift by 1
}
return str;
}
// reverse the string
public static void reverse(String str)
{
for (int i = str.Length - 1; i >= 0; i--)
Console.Write(str[i]);
}
// Driver Code
public static void Main(string[] args)
{
int num = 59;
Console.Write("Binary of num 59 is: ");
reverse(DecimalToBinary(num));
}
}
// this code was contributed by phasing17
Javascript
<script>
// JavaScript program to implement the approach
// function to convert decimal to binary
function DecimalToBinary(num)
{
var str = "";
while (num)
{
// adding the result of num & 1 to str
if (num & 1) // 1
str += '1';
else // 0
str += '0';
// Right Shift by 1
num >>= 1;
}
return str;
}
// function to print reverse of str
function reverse(str)
{
var res = "";
for (var i = str.length - 1; i >= 0; i--)
res += (str[i]);
document.write(res);
}
// Driver Code
var num = 59;
document.write("Binary of num " + num + " is: ");
// function call
reverse(DecimalToBinary(num));
// This code is contributed by phasing17
</script>
Python3
# Python3 program to implement the above approach
# function to convert the decimal number
# to binary number
def DecimalToBinary(num):
strs = ""
while num:
# if (num & 1) = 1
if (num & 1):
strs += "1"
# if (num & 1) = 0
else:
strs += "0"
# right shift by 1
num >>= 1
return strs
# function to reverse the string
def reverse(strs):
print(strs[::-1])
# Driver Code
num = 59
print("Binary of num 59 is:", end=" ")
reverse(DecimalToBinary(num))
# This code is contributed by phasing17
OutputBinary of num 59 is: 111011
Time Complexity: Â O(log n) & Auxiliary Space: O(1)Â
Decimal to binary conversion can also be done without using arrays.Â
C++
// C++ implementation of the approach
#include <cmath>
#include <iostream>
using namespace std;
#define ull unsigned long long int
// Function to return the binary
// equivalent of decimal value N
int decimalToBinary(int N)
{
// To store the binary number
ull B_Number = 0;
int cnt = 0;
while (N != 0) {
int rem = N % 2;
ull c = pow(10, cnt);
B_Number += rem * c;
N /= 2;
// Count used to store exponent value
cnt++;
}
return B_Number;
}
// Driver code
int main()
{
int N = 17;
cout << decimalToBinary(N);
return 0;
}
// This code is contributed by Sania Kumari Gupta (kriSania804)
C
// C implementation of the approach
#include <math.h>
#include <stdio.h>
#define ull unsigned long long int
// Function to return the binary
// equivalent of decimal value N
int decimalToBinary(int N)
{
// To store the binary number
ull B_Number = 0;
int cnt = 0;
while (N != 0) {
int rem = N % 2;
ull c = pow(10, cnt);
B_Number += rem * c;
N /= 2;
// Count used to store exponent value
cnt++;
}
return B_Number;
}
// Driver code
int main()
{
int N = 17;
printf("%u", decimalToBinary(N));
return 0;
}
// This code is contributed by Sania Kumari Gupta (kriSania804)
Java
// Java implementation of the approach
import java.io.*;
class GFG
{
// Function to return the binary
// equivalent of decimal value N
static int decimalToBinary(int N)
{
// To store the binary number
int B_Number = 0;
int cnt = 0;
while (N != 0)
{
int rem = N % 2;
double c = Math.pow(10, cnt);
B_Number += rem * c;
N /= 2;
// Count used to store exponent value
cnt++;
}
return B_Number;
}
// Driver code
public static void main (String[] args)
{
int N = 17;
System.out.println (decimalToBinary(N));
}
}
// This code is contributed by ajit.
C#
// C# implementation of the approach
using System;
class GFG
{
// Function to return the binary
// equivalent of decimal value N
static int decimalToBinary(int N)
{
// To store the binary number
int B_Number = 0;
int cnt = 0;
while (N != 0)
{
int rem = N % 2;
int c = (int)Math.Pow(10, cnt);
B_Number += rem * c;
N /= 2;
// Count used to store exponent value
cnt++;
}
return B_Number;
}
// Driver code
static public void Main ()
{
int N = 17;
Console.Write(decimalToBinary(N));
}
}
// This code is contributed by Tushil.
Javascript
<script>
// javascript implementation of the approach
// Function to return the binary
// equivalent of decimal value N
function decimalToBinary(N)
{
// To store the binary number
var B_Number = 0;
var cnt = 0;
while (N != 0)
{
var rem = N % 2;
var c = Math.pow(10, cnt);
B_Number += rem * c;
N = parseInt(N/2);
// Count used to store exponent value
cnt++;
}
return B_Number;
}
// Driver code
var N = 17;
document.write(decimalToBinary(N));
// This code is contributed by Princi Singh
</script>
Python3
# Python3 implementation of the approach
# Function to return the binary
# equivalent of decimal value N
def decimalToBinary(N):
# To store the binary number
B_Number = 0
cnt = 0
while (N != 0):
rem = N % 2
c = pow(10, cnt)
B_Number += rem * c
N //= 2
# Count used to store exponent value
cnt += 1
return B_Number
# Driver code
N = 17
print(decimalToBinary(N))
# This code is contributed by
# SHUBHAMSINGH10
Time complexity: O(logn)Â & Auxiliary Space: O(1)Â
Note that this method is similar to the one where we convert Binary to Decimal as discussed in this post.
There is yet another method that converts any Decimal Number to its Binary form. The idea is to use bitset.
Below is the implementation of the above approach.Â
C++
//C++ program to convert a decimal number
//to its binary form.
//including header file
#include <bits/stdc++.h>
using namespace std;
//Function to convert a decimal number
//to its binary form
string decimalToBinary(int n)
{
//finding the binary form of the number and
//converting it to string.
string s = bitset<64> (n).to_string();
//Finding the first occurrence of "1"
//to strip off the leading zeroes.
const auto loc1 = s.find('1');
if(loc1 != string::npos)
return s.substr(loc1);
return "0";
}
//Driver Code
int main()
{
int n = 17;
//Function call
cout << decimalToBinary(n);
return 0;
}
//This code is contributed by yashbeersingh42
Java
// Java program to convert a decimal number to its binary
// form
import java.util.*;
class DecimalToBinary {
// Function to convert a decimal number to its binary
// form
public static String decimalToBinary(int n)
{
// Finding the binary form of the number and
// converting it to a string
String s = Integer.toBinaryString(n);
// Finding the first occurrence of "1" to strip off
// the leading zeroes
int loc1 = s.indexOf("1");
if (loc1 != -1) {
return s.substring(loc1);
}
return "0";
}
// Driver code
public static void main(String[] args)
{
int n = 17;
// Function call
System.out.println(decimalToBinary(n));
}
}
// This code is contributed by phasing17
C#
// C# program to convert a decimal number
// to its binary form.
using System;
class HelloWorld {
// Function to convert a decimal number
// to its binary form
public static String decimalToBinary(int n)
{
// finding the binary form of the number and
//converting it to string.
String s = Convert.ToString(n, 2);
return s;
}
static void Main() {
int n = 17;
//Function call
Console.WriteLine(decimalToBinary(n));
}
}
// The code is contributed by Nidhi goel.
Javascript
// Javascript program to convert a decimal number
// to its binary form.
// Function to convert a decimal number
// to its binary form
function decimalToBinary( n)
{
// finding the binary form of the number and
// converting it to string.
const s = n.toString(2);
return s;
}
// Driver Code
let n = 17;
// Function call
console.log(decimalToBinary(n));
// This code is contributed by imruhrbf8.
Python3
# Python program to convert a decimal number
# to its binary form.
# Function to convert a decimal number
# to its binary form
def decimalToBinary( n):
# finding the binary form of the number and
# converting it to string.
s = bin(n)[2:]
# Finding the first occurrence of "1"
# to strip off the leading zeroes.
# const auto loc1 = s.find('1')
loc1 = s[s.index('1'):]
return loc1
return "0"
# Driver Code
n = 17
# Function call
print(decimalToBinary(n))
Time complexity: O(logn)Â & Auxiliary Space: O(1)Â
Another Approach
C++
// C++ program to convert Decimal to Binary Number
#include <bits/stdc++.h>
using namespace std;
int main()
{
// input number
int number = 15;
int n = (int)(log2(number));
// binary output
// using the inbuilt function
cout << "the binary number is : "
<< bitset<64>(number).to_string().substr(64 - n
- 1);
}
// This code is written by phasing17
Java
//To convert Decimal to Binary Number//
import java.util.*;
public class Main{
public static void main(String [] args){
//input//
int number =15;
//output//
System.out.println("the binary number is : "+ Integer.toString(number,2));
//This code is written by ZEESHAN AHMAD//
}
}
C#
// To convert Decimal to Binary Number//
using System;
class GFG{
public static void Main(){
// input//
int number =15;
//output//
Console.WriteLine("the binary number is : "+ Convert.ToString(number, 2));
}
}
// This code is contributed by code_hunt.
Javascript
// JavaScript program to convert Decimal to Binary Number
// input number
var number = 15;
// binary output
// using the inbuilt function
console.log("the binary number is :", number.toString(2));
// This code is written by phasing17
Python3
# Python3 program to convert Decimal to Binary Number
# input number
number = 15
# binary output
# using the inbuilt function
print("the binary number is :", bin(number)[2::])
# This code is written by phasing17
Outputthe binary number is : 1111
Time complexity: O(logn)Â & Auxiliary Space: O(1)Â
Â
Last Updated :
22 Mar, 2024
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