Given a number to find the first and last digit of a number.
Examples:
Input : 12345
Output : First digit: 1
last digit : 5
Input : 98562
Output : First digit: 9
last digit : 2
To find last digit of a number, we use modulo operator %. When modulo divided by 10 returns its last digit.
Suppose if n = 1234
then last Digit = n % 10 => 4
To find first digit of a number is little expensive than last digit. To find first digit of a number we divide the given number by 10 until number is greater than 10. At the end we are left with the first digit.
Approach 1 (With loop):
C++
// Program to find first and last// digits of a number#include <bits/stdc++.h>using namespace std;// Find the first digitint firstDigit(int n){ // Remove last digit from number // till only one digit is left while (n >= 10) n /= 10; // return the first digit return n;}// Find the last digitint lastDigit(int n){ // return the last digit return (n % 10);}// Driver programint main(){ int n = 98562; cout << firstDigit(n) << " " << lastDigit(n) << endl; return 0;} |
Java
// Java Program to find first and last// digits of a numberimport java.util.*;import java.lang.*;public class GfG{ // Find the first digit public static int firstDigit(int n) { // Remove last digit from number // till only one digit is left while (n >= 10) n /= 10; // return the first digit return n; } // Find the last digit public static int lastDigit(int n) { // return the last digit return (n % 10); } // driver function public static void main(String argc[]) { int n = 98562; System.out.println(firstDigit(n) + " " + lastDigit(n)); }}// This code is contributed by Sagar Shukla |
Python3
# Python3 program to find first and # last digits of a number# Find the first digitdef firstDigit(n) : # Remove last digit from number # till only one digit is left while n >= 10: n = n / 10; # return the first digit return int(n)# Find the last digitdef lastDigit(n) : # return the last digit return (n % 10)# Driver Coden = 98562;print(firstDigit(n), end = " ") print(lastDigit(n))# This code is contributed by rishabh_jain |
C#
// C# Program to find first and last// digits of a numberusing System;public class GfG{ // Find the first digit public static int firstDigit(int n) { // Remove last digit from number // till only one digit is left while (n >= 10) n /= 10; // return the first digit return n; } // Find the last digit public static int lastDigit(int n) { // return the last digit return (n % 10); } // driver function public static void Main() { int n = 98562; Console.WriteLine(firstDigit(n) + " " + lastDigit(n)); }}// This code is contributed by vt_m |
PHP
<?php// PHP Program to find first // and last digits of a number// Find the first digitfunction firstDigit($n){ // Remove last digit from number // till only one digit is left while ($n >= 10) $n /= 10; // return the first digit return (int)$n;}// Find the last digitfunction lastDigit($n){ // return the last digit return ((int)$n % 10);}// Driver Code$n = 98562;echo firstDigit($n) . " " . lastDigit($n) . "\n";// This code is contributed // by Akanksha Rai(Abby_akku) |
Javascript
<script>// javascript Program to find first and last// digits of a number // Find the first digit function firstDigit(n) { // Remove last digit from number // till only one digit is left while (n >= 10) n /= 10; // return the first digit return Math.floor(n); } // Find the last digit function lastDigit(n) { // return the last digit return Math.floor(n % 10); }// Driver code let n = 98562; document.write(firstDigit(n) + " " + lastDigit(n)); // This code is contributed by sanjoy_62.</script> |
Output
9 2
Time Complexity: O(log10n)
Auxiliary Space: O(1)
Approach 2 (Without loop)
C++
// Program to find first and last // digits of a number#include <bits/stdc++.h>using namespace std;// Find the first digitint firstDigit(int n){ // Find total number of digits - 1 int digits = (int)log10(n); // Find first digit n = (int)(n / pow(10, digits)); // Return first digit return n;}// Find the last digitint lastDigit(int n){ // return the last digit return (n % 10);}// Driver programint main(){ int n = 98562; cout << firstDigit(n) << " " << lastDigit(n) << endl; return 0;} |
Java
// Java program to find first and // last digits of a numberimport java.math.*;class GFG { // Find the first digit static int firstDigit(int n) { // Find total number of digits - 1 int digits = (int)(Math.log10(n)); // Find first digit n = (int)(n / (int)(Math.pow(10, digits))); // Return first digit return n; } // Find the last digit static int lastDigit(int n) { // return the last digit return (n % 10); } // Driver program public static void main(String args[]) { int n = 98562; System.out.println(firstDigit(n) + " " + lastDigit(n)); }}// This code is contributed by Nikita Tiwari. |
Python3
# Python3 program to find first # and last digits of a numberimport math# Find the first digitdef firstDigit(n) : # Find total number of digits - 1 digits = (int)(math.log10(n)) # Find first digit n = (int)(n / pow(10, digits)) # Return first digit return n;# Find the last digitdef lastDigit(n) : # return the last digit return (n % 10)# Driver Coden = 98562;print(firstDigit(n), end = " ") print(lastDigit(n))# This code is contributed by rishabh_jain |
C#
// C# program to find first and // last digits of a numberusing System;class GFG { // Find the first digit static int firstDigit(int n) { // Find total number of digits - 1 int digits = (int)(Math.Log10(n)); // Find first digit n = (int)(n / (int)(Math.Pow(10, digits))); // Return first digit return n; } // Find the last digit static int lastDigit(int n) { // return the last digit return (n % 10); } // Driver program public static void Main() { int n = 98562; Console.WriteLine(firstDigit(n) + " " + lastDigit(n)); }}// This code is contributed by vt_m. |
PHP
<?php// Program to find first and last // digits of a number // Find the first digit function firstDigit($n) { // Find total number of digits - 1 $digits = (int)log10($n); // Find first digit $n = (int)($n / pow(10, $digits)); // Return first digit return $n; } // Find the last digit function lastDigit($n) { // return the last digit return ($n % 10); } // Driver Code $n = 98562; echo firstDigit($n) , " ", lastDigit($n), "\n"; // This code is contributed by ajit?> |
Javascript
<script>// JavaScript program to find first // and last digits of a number// Find the first digitfunction firstDigit(n){ // Find total number of digits - 1 let digits = Math.floor(Math.log(n)/Math.log(10)) // Find first digit n = Math.floor(n / Math.pow(10, digits)) // Return first digit return n;}// Find the last digitfunction lastDigit(n){ // return the last digit return (n % 10)}// Driver Codelet n = 98562;document.write(firstDigit(n)," ") document.write(lastDigit(n),"</br>")// This code is contributed by shinjanpatra</script> |
Output
9 2
Time Complexity: O(log(log10(n))
Auxiliary Space: O(1)
Important note: log10() is a mathematical function present in math.h header file. It returns log base 10 value of the passed parameter to log10() function.
Approach 3: Using string operation to_string
First converting number to string and then first char of string and last character of string – ‘0’ is our ans.
C++
#include <iostream>using namespace std;int main() { int n = 34356; string s = to_string(n); int first_digit = s.front() - '0'; int last_digit = s.back() - '0'; cout<<"First digit of "<<n<<" is "<<first_digit<<endl; cout<<"Last digit of "<<n<<" is "<<last_digit<<endl;} |
Java
import java.util.*;public class Main { public static void main(String[] args) { int n = 34356; String s = Integer.toString(n); int first_digit = s.charAt(0) - '0'; int last_digit = s.charAt(s.length() - 1) - '0'; System.out.println("First digit of " + n + " is " + first_digit); System.out.println("Last digit of " + n + " is " + last_digit); }} |
Python3
# Python program to extract first and last digits of a number# including comments and no empty lines# take an integer inputn = 34356# convert the integer to strings = str(n)# extract first and last digits from the stringfirst_digit = int(s[0])last_digit = int(s[-1])# print the resultsprint("First digit of", n, "is", first_digit)print("Last digit of", n, "is", last_digit) |
C#
using System;public class GFG{ static public void Main (){ int n = 34356; string s = n.ToString(); int first_digit = s[0] - '0'; int last_digit = s[s.Length - 1] - '0'; Console.WriteLine("First digit of {0} is {1}", n, first_digit); Console.WriteLine("Last digit of {0} is {1}", n, last_digit); }} |
Javascript
let n = 34356;let s = n.toString();let first_digit = parseInt(s.charAt(0));let last_digit = parseInt(s.charAt(s.length-1));console.log("First digit of " + n + " is " + first_digit);console.log("Last digit of " + n + " is " + last_digit); |
Output
First digit of 34356 is 3 Last digit of 34356 is 6
Time Complexity: O(n)
Auxiliary Space: O(n)
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