'Coding has over 700 languages', '67% of programming jobs aren’t in the technology industry', 'Coding is behind almost everything that is powered by electricity'
Last Updated: Feb 12, 2024
Easy

What are Non-alphanumeric Characters?

Author Sonu Deo
0 upvote
gp-icon
Basics of C++
Free guided path
9 chapters
99+ problems
gp-badge
Earn badges and level up

Introduction

First, let’s talk about Alphanumeric characters which include letters (Lowercase and Uppercase) and numbers. For example, “Coding11Ninjas” is an alphanumeric string as all the characters in the string are Alphanumeric characters.

Non-alphanumeric characters refer to those characters that are neither alphabets (a-z) nor numbers(0-9). Non-alphanumeric characters include symbols, punctuation, or other special characters such as @ # $ % & * ! ? ; etc. 
 

Introduction

Non-alphanumeric Characters

Consider your keyboard and check for all the characters that do not belong to any alphabet or any digit those all characters along with many more characters combined are called Non-alphanumeric Characters. Non-alphanumeric characters can be grouped as Punctuation characters! @ # & ( ) – [ { } ] : ; ', ? / * and symbol characters ` ~ $ ^ + = < > “. For example “@#$*+==*(_” is a Nonalphanumeric String.

Now we will look after some of the commonly used Non-alphanumeric characters along with their symbols.

List of commonly used Non-alphanumeric Characters

List of commonly used Non-alphanumeric Characters

List of commonly used Non-alphanumeric Characters

You can also do a free certification of Basics of C++.

Get the tech career you deserve, faster!
Connect with our expert counsellors to understand how to hack your way to success
User rating 4.7/5
1:1 doubt support
95% placement record
Akash Pal
Senior Software Engineer
326% Hike After Job Bootcamp
Himanshu Gusain
Programmer Analyst
32 LPA After Job Bootcamp
After Job
Bootcamp

Removing Non-alphanumeric characters from a string

In most cases, we come across some strings having non-alphanumeric characters that need to be converted into Alphanumeric strings because of limitations of devices in processing Non-alphanumeric characters.

Now let’s look at some of the methods to do that:

Using ASCII values

Because alphanumeric characters have ASCII values of [65, 90] for uppercase alphabets, [97, 122] for lowercase alphabets, and [48, 57] for digits. As a result, go through the string character by character and get the ASCII value of each character. If the ASCII value is not in one of the above three ranges, the character is Non-alphanumeric. As a result, skip such characters and add the rest to another string before printing it.

Implementation in c++:

#include <bits/stdc++.h>
using namespace std;
int main(){
    string str = "Coding #*( $ Ninj@$";
    string ans = "";
    for(int i=0;i<str.size();i++){
        int ASCII = (int)str[i];
        if(ASCII>=48 && ASCII<=57){ //for digits
            ans += str[i];
        }
        else if(ASCII>=65 && ASCII<=90){ //for uppercase
            ans += str[i];
        }
        else if(ASCII>=97 && ASCII<=122){ //for lowercase
            ans += str[i];
        }
        else continue;  
    }
    cout<<ans;
}


Output:

CodingNinj

Using in-built functions:

Programming languages have several builtin functions to check for alphanumeric characters

Implementation in c++:

#include <bits.stdc++.h>
using namespace std;
int main(){
    string str = "Coding #*( $ Ninj@$";
    string ans = "";
    for(int i=0;i<str.size();i++){
        // check for alphanumeric characters
        if(isalnum(str[i])){
            ans += str[i];
        }  
        else continue;
    }
    cout<<ans;
}


Output:

CodingNinj

 

You can try and compile with the help of online c++ compiler.

Using Regular Expression

Since the required string contains only characters from 1-9, a-z and A-Z so we can filter the ans string using regex [^a-zA-Z0-9]

Implementation in Java:

class Coding_ninjas{
    public static void main(String args[])
    {
        String str1 = "Coding #*( $ Ninj@$";
        //replace all characters other than alphanumeric
        str1 = str1.replaceAll("[^a-zA-Z0-9]", "");
        System.out.println(str1);
    }
}


Output:

CodingNinj

Fibonacci Series in C++
 

Non-alphanumeric Characters in Passwords

Non-alphanumeric characters make good passwords because they use symbols and punctuation, which are difficult to crack if someone tries to hack your account. It is for their enhanced security, which is mostly used in our social media accounts, as indicated by comments from people who have used it previously. They use numerals, Arabic signs, upper case letters, numbers, and lower case letters to perfectly secure your account. As a result, people nowadays prefer to use passwords on computers that contain non-alphanumeric characters.

Most sites require passwords to have at least 8-12 characters and to be unique as well as strong. Passwords that are formed in a different and unique manner are considered strong, or else the site will tell you to change them as soon as possible, and there are various tools available nowadays to create unique passwords. Hackers have become experts at cracking passwords and stealing personal information, so it is critical to create strong passwords yourself or with the assistance of a strong password-creation tool.

Frequently Asked Questions

What are Non-alphanumeric Characters?

Non-alphanumeric characters are characters other than letters and numbers, i.e., all the characters on the keyboard which are not letters and numbers are Nonalphamuneric characters.

Why are Non-alphanumeric Characters important?

These characters are used for creating strong passwords, and for various important sites, it is a must to have at least one such character. Also, these are used for denoting various scientific terms.

What are ASCII values?

ASCII values are just a character encoding scheme used for electronic communication, each character is represented by a fixed ASCII value. Its full form is American Standard Code for information interchange.

Conclusion

In this article, we discussed Non-alphanumeric characters and their examples. We looked for different methods of removing non-alphanumeric characters from the string and the main use of non-alphanumeric characters as passwords for different websites.

If you think this blog has helped you enhance your knowledge about the above question, and if you would like to learn more, check out our articles. 

And many more on our website.

Visit our website to read more such blogs. Make sure you enroll in the courses we provide, take mock tests, solve problems, and interview puzzles. Also, you can pay attention to interview stuff- interview experiences and an interview bundle for placement preparations.

Previous article
Convert char to int in C and C++
Next article
Differentiating between C & C++ programming languages
Guided path
Free
gridgp-icon
Basics of C++
9 chapters
104+ Problems
gp-badge
Earn badges and level up
Live masterclass