Check If a Character Is a Digit or Not in C / C++ / Java / Python / C#

Programs to check if a character is a digit or not have been shown here. The numeric digits are 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.

Page content(s):

1. Algorithm

2. Pseudocode

3. Time complexity

4. Flowchart

5. Program & output: using ASCII value

 5.1. C

 5.2. C++

 5.3. Java

 5.4. Python

 5.5. C#

1. Algorithm to Check If a Character Is a Digit or Not

1. Take the character x as input.

2. Check if the ASCII value of x is between 48 and 57.

3. If step 2 is true declare the character x as digit x.

4. If step 2 is false declare the character x is not a digit.

2. Pseudocode to Check If a Character Is a Digit or Not

Input : A character $x$

Output : $x$ is a digit or not

1. Procedure checkDigit($x$):

2. If ASCII($x$) $\in [48, 57]$:

3. Return "Digit"

4. Else:

5. Return "Not a digit"

6. End Procedure

3. Time complexity to Check If a Character Is a Digit or Not

Time Complexity: O(1)

4. Flowchart to Check If a Character Is a Digit or Not

5. Program to Check If a Character Is a Digit or Not

This section covers the C, C++, Java, Python and C# programs to check if a character is a digit or not. The programs declare the character as a digit if the ASCII value of the character lies between 48 and 57.

5.1. C Program to Check If a Character Is a Digit or Not

Code has been copied

/***************************
     alphabetacoder.com
C program to check if a 
character is a digit or not
****************************/

#include <stdio.h>

int main() {
    // declare variables
    char x;

    // take input 
    printf("Enter a character: ");
    scanf("%c", & x);

    // check if the character 
    // is a digit or not
    // Range of ASCII values of digits
    //  0 to 9 are from 48 to 57 
    if (x >= 48 && x <= 57)
        printf("It is the digit %c", x);
    else
        printf("%c is not a digit", x);

    return 0;
}

Output

Case 1:

Enter a character: 8

It is the digit 8

Case 2:

Enter a character: 0

It is the digit 0

Case 3:

Enter a character: a

a is not a digit

5.2. C++ Program to Check If a Character Is a Digit or Not

Code has been copied

/***************************
     alphabetacoder.com
C++ program to check if a 
character is a digit or not
****************************/

#include <iostream>

using namespace std;

int main() {
    // declare variables
    char x;

    // take input 
    cout << "Enter a character: ";
    cin >> x;

    // check if the character 
    // is a digit or not
    // Range of ASCII values of digits
    //  0 to 9 are from 48 to 57 
    if (x >= 48 && x <= 57)
        cout << "It is the digit " << x;
    else
        cout << x << " is not a digit";

    return 0;
}

Output

Case 1:

Enter a character: 1

It is the digit 1

Case 2:

Enter a character: 5

It is the digit 5

Case 3:

Enter a character: x

x is not a digit

5.3. Java Program to Check If a Character Is a Digit or Not

Code has been copied

/***************************
     alphabetacoder.com
Java program to check if a 
character is a digit or not
****************************/

import java.util.Scanner;
public class Main {
    public static void main(String args[]) {
        // declare variables
        char x;

        // declare an instance of scanner class
        Scanner sc = new Scanner(System.in);

        // take input 
        System.out.print("Enter a character: ");
        x = sc.next().charAt(0);

        // check if the character 
        // is a digit or not
        // Range of ASCII values of digits
        //  0 to 9 are from 48 to 57 
        if (x >= 48 && x <= 57)
            System.out.print("It is the digit " + x);
        else
            System.out.print(x + " is not a digit");
    }
}

Output

Case 1:

Enter a character: 3

It is the digit 3

Case 2:

Enter a character: 4

It is the digit 4

Case 3:

Enter a character: p

p is not a digit

5.4. Python Program to Check If a Character Is a Digit or Not

Code has been copied

# *****************************
#     alphabetacoder.com
# Python program to check if a
# character is a digit or not
# *****************************

# take input
x = input("Enter a character: ")

# check if the character
# is a digit or not
# Range of ASCII values of digits
#  0 to 9 are from 48 to 57
if ord(x) >= 48 and ord(x) <= 57:
    print("It is the digit ", x)
else:
    print(x, " is not a digit")

Output

Case 1:

Enter a character: 2

It is the digit 2

Case 2:

Enter a character: 6

It is the digit 6

Case 3:

Enter a character: *

* is not a digit

5.5. C# Program to Check If a Character Is a Digit or Not

Code has been copied

/***************************
     alphabetacoder.com
C# program to check if a 
character is a digit or not
****************************/

using System;

namespace CheckDigit {
    class Program {
        static void Main(string[] args) {
            // declare variables
            char x;

            // take input
            Console.Write("Enter a character: ");
            x = Console.ReadLine()[0];

            // check if the character 
            // is a digit or not
            // Range of ASCII values of digits
            //  0 to 9 are from 48 to 57 
            if (x >= 48 && x <= 57)
                Console.WriteLine("It is the digit " + x);
            else
                Console.WriteLine(x + " is not a digit");

            // wait for user to press any key
            Console.ReadKey();
        }
    }
}

Output

Case 1:

Enter a character: 7

It is the digit 7

Case 2:

Enter a character: 9

It is the digit 9

Case 3:

Enter a character: !

! is not a digit