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Program for decimal to hexadecimal conversion
  • Difficulty Level : Easy
  • Last Updated : 12 May, 2021

Given a decimal number as input, we need to write a program to convert the given decimal number into equivalent hexadecimal number. i.e convert the number with base value 10 to base value 16.

Hexadecimal numbers uses 16 values to represent a number. Numbers from 0-9 are expressed by digits 0-9 and 10-15 are represented by characters from A – F.

Examples:  

Input : 116
Output: 74

Input : 10
Output: A

Input : 33
Output: 21

Algorithm:

  1. Store the remainder when the number is divided by 16 in a temporary variable temp. If temp is less than 10, insert (48 + temp) in a character array otherwise if temp is greater than or equals to 10, insert (55 + temp) in the character array.
  2. Divide the number by 16 now
  3. Repeat the above two steps until the number is not equal to 0.
  4. Print the array in reverse order now.

Example



If the given decimal number is 2545. 

Step 1: Calculate remainder when 2545 is divided by 16 is 1. Therefore, temp = 1. As temp is less than 10. So, arr[0] = 48 + 1 = 49 = ‘1’. 
Step 2: Divide 2545 by 16. New number is 2545/16 = 159. 
Step 3: Calculate remainder when 159 is divided by 16 is 15. Therefore, temp = 15. As temp is greater than 10. So, arr[1] = 55 + 15 = 70 = ‘F’. 
Step 4: Divide 159 by 16. New number is 159/16 = 9. 
Step 5: Calculate remainder when 9 is divided by 16 is 9. Therefore, temp = 9. As temp is less than 10. So, arr[2] = 48 + 9 = 57 = ‘9’. 
Step 6: Divide 9 by 16. New number is 9/16 = 0. 
Step 7: Since number becomes = 0. Stop repeating steps and print the array in reverse order. Therefore, the equivalent hexadecimal number is 9F1.

Below diagram shows an example of converting the decimal number 2545 to an equivalent hexadecimal number.  

Below is the implementation of above idea. 

C++




// C++ program to convert a decimal
// number to hexadecimal number
 
#include <iostream>
using namespace std;
 
// function to convert decimal to hexadecimal
void decToHexa(int n)
{
    // char array to store hexadecimal number
    char hexaDeciNum[100];
 
    // counter for hexadecimal number array
    int i = 0;
    while (n != 0) {
        // temporary variable to store remainder
        int temp = 0;
 
        // storing remainder in temp variable.
        temp = n % 16;
 
        // check if temp < 10
        if (temp < 10) {
            hexaDeciNum[i] = temp + 48;
            i++;
        }
        else {
            hexaDeciNum[i] = temp + 55;
            i++;
        }
 
        n = n / 16;
    }
 
    // printing hexadecimal number array in reverse order
    for (int j = i - 1; j >= 0; j--)
        cout << hexaDeciNum[j];
}
 
// Driver program to test above function
int main()
{
    int n = 2545;
 
    decToHexa(n);
 
    return 0;
}

Java




// Java program to convert a decimal
// number to hexadecimal number
import java.io.*;
 
class GFG {
    // function to convert decimal to hexadecimal
    static void decToHexa(int n)
    {
        // char array to store hexadecimal number
        char[] hexaDeciNum = new char[100];
 
        // counter for hexadecimal number array
        int i = 0;
        while (n != 0) {
            // temporary variable to store remainder
            int temp = 0;
 
            // storing remainder in temp variable.
            temp = n % 16;
 
            // check if temp < 10
            if (temp < 10) {
                hexaDeciNum[i] = (char)(temp + 48);
                i++;
            }
            else {
                hexaDeciNum[i] = (char)(temp + 55);
                i++;
            }
 
            n = n / 16;
        }
 
        // printing hexadecimal number array in reverse
        // order
        for (int j = i - 1; j >= 0; j--)
            System.out.print(hexaDeciNum[j]);
    }
 
    // driver program
    public static void main(String[] args)
    {
        int n = 2545;
        decToHexa(n);
    }
}
 
// Contributed by Pramod Kumar

Python3




# Python3 program to
# convert a decimal
# number to hexadecimal
# number
 
# function to convert
# decimal to hexadecimal
 
 
def decToHexa(n):
 
    # char array to store
    # hexadecimal number
    hexaDeciNum = ['0'] * 100
 
    # counter for hexadecimal
    # number array
    i = 0
    while(n != 0):
 
        # temporary variable
        # to store remainder
        temp = 0
 
        # storing remainder
        # in temp variable.
        temp = n % 16
 
        # check if temp < 10
        if(temp < 10):
            hexaDeciNum[i] = chr(temp + 48)
            i = i + 1
        else:
            hexaDeciNum[i] = chr(temp + 55)
            i = i + 1
        n = int(n / 16)
 
    # printing hexadecimal number
    # array in reverse order
    j = i - 1
    while(j >= 0):
        print((hexaDeciNum[j]), end="")
        j = j - 1
 
 
# Driver Code
n = 2545
decToHexa(n)
 
# This code is contributed
# by mits.

C#




// C# program to convert a decimal
// number to hexadecimal number
using System;
 
class GFG {
    // function to convert decimal
    // to hexadecimal
    static void decToHexa(int n)
    {
        // char array to store
        // hexadecimal number
        char[] hexaDeciNum = new char[100];
 
        // counter for hexadecimal number array
        int i = 0;
        while (n != 0) {
            // temporary variable to
            // store remainder
            int temp = 0;
 
            // storing remainder in temp
            // variable.
            temp = n % 16;
 
            // check if temp < 10
            if (temp < 10) {
                hexaDeciNum[i] = (char)(temp + 48);
                i++;
            }
            else {
                hexaDeciNum[i] = (char)(temp + 55);
                i++;
            }
 
            n = n / 16;
        }
 
        // printing hexadecimal number
        // array in reverse order
        for (int j = i - 1; j >= 0; j--)
            Console.Write(hexaDeciNum[j]);
    }
 
    // Driver Code
    public static void Main(String[] args)
    {
        int n = 2545;
        decToHexa(n);
    }
}
 
// This code is contributed by Nitin Mittal.

PHP




<?php
// PHP program to convert
// a decimal number to
// hexadecimal number
 
// function to convert
// decimal to hexadecimal
function decToHexa($n)
{
    // char array to store
    // hexadecimal number
    $hexaDeciNum;
     
    // counter for hexadecimal
    // number array
    $i = 0;
    while($n != 0)
    {
        // temporary variable
        // to store remainder
        $temp = 0;
         
        // storing remainder
        // in temp variable.
        $temp = $n % 16;
         
        // check if temp < 10
        if($temp < 10)
        {
            $hexaDeciNum[$i] = chr($temp + 48);
            $i++;
        }
        else
        {
            $hexaDeciNum[$i] = chr($temp + 55);
            $i++;
        }
         
        $n = (int)($n / 16);
    }
     
    // printing hexadecimal number
    // array in reverse order
    for($j = $i - 1; $j >= 0; $j--)
        echo $hexaDeciNum[$j];
}
 
// Driver Code
$n = 2545;
decToHexa($n);
 
// This code is contributed
// by mits.
?>

Javascript




<script>
 
// Javascript program to convert a decimal
// number to hexadecimal number
 
// function to convert decimal to hexadecimal
function decToHexa(n)
{
    // char array to store hexadecimal number
    var hexaDeciNum = Array.from({length: 100},
                      (_, i) => 0);
 
    // counter for hexadecimal number array
    var i = 0;
    while (n != 0) {
        // temporary variable to store remainder
        var temp = 0;
 
        // storing remainder in temp variable.
        temp = n % 16;
 
        // check if temp < 10
        if (temp < 10) {
            hexaDeciNum[i] =
            String.fromCharCode(temp + 48);
            i++;
        }
        else {
            hexaDeciNum[i] =
            String.fromCharCode(temp + 55);
            i++;
        }
 
        n = parseInt(n / 16);
    }
 
    // printing hexadecimal number array in reverse
    // order
    for (j = i - 1; j >= 0; j--)
        document.write(hexaDeciNum[j]);
}
 
// driver program
var n = 2545;
decToHexa(n);
 
// This code contributed by shikhasingrajput
 
</script>
Output
9F1

Using Predefined function

Java




// Java program to convert a decimal
// number to hexadecimal number
import java.io.*;
 
class GFG {
    public static void decToHexa(int n)
    {
        System.out.println(Integer.toHexString(n));
    }
    public static void main(String[] args)
    {
 
        int n = 2545;
        decToHexa(n);
    }
}
Output
9f1

This article is contributed by Harsh Agarwal. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.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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