Remove all characters other than alphabets from string

Given a string consisting of alphabets and others characters, remove all the characters other than alphabets and print the string so formed. 

Examples:

Input : $Gee*k;s..fo, r’Ge^eks?
Output : GeeksforGeeks

Input : P&ra+$BHa;;t*ku, ma$r@@s#in}gh
Output : PraBHatkumarsingh

To remove all the characters other than alphabets(a-z) && (A-Z), we just compare the character with the ASCII value, and for the character whose value does not lie in the range of alphabets, we remove those characters using string erase function. 

Implementation:

C++

// CPP program to remove all the
// characters other than alphabets
#include <bits/stdc++.h>
using namespace std;

// function to remove characters and
// print new string
void removeSpecialCharacter(string s)
{
    for (int i = 0; i < s.size(); i++) {

        // Finding the character whose
        // ASCII value fall under this
        // range
        if (s[i] < 'A' || s[i] > 'Z' && s[i] < 'a'
            || s[i] > 'z') {
            // erase function to erase
            // the character
            s.erase(i, 1);
            i--;
        }
    }
    cout << s;
}

// driver code
int main()
{
    string s = "$Gee*k;s..fo, r'Ge^eks?";
    removeSpecialCharacter(s);
    return 0;
}

Java

// Java program to remove all the characters
// other than alphabets

class GFG
{

    // function to remove characters and
    // print new string
    static void removeSpecialCharacter(String s)
    {
        for (int i = 0; i < s.length(); i++)
        {

            // Finding the character whose
            // ASCII value fall under this
            // range
            if (s.charAt(i) < 'A' || s.charAt(i) > 'Z' &&
                    s.charAt(i) < 'a' || s.charAt(i) > 'z')
            {

                // erase function to erase
                // the character
                s = s.substring(0, i) + s.substring(i + 1);
                i--;
            }
        }
        System.out.print(s);
    }

    // Driver code
    public static void main(String[] args)
    {
        String s = "$Gee*k;s..fo, r'Ge^eks?";
        removeSpecialCharacter(s);
    }
}

// This code is contributed by Rajput-Ji

Python3

# Python3 program to remove all the
# characters other than alphabets

# function to remove characters and
# print new string
def removeSpecialCharacter(s):

    i = 0

    while i < len(s):

        # Finding the character whose
        # ASCII value fall under this
        # range
        if (ord(s[i]) < ord('A') or
            ord(s[i]) > ord('Z') and
            ord(s[i]) < ord('a') or
            ord(s[i]) > ord('z')):

            # erase function to erase
            # the character
            del s[i]
            i -= 1
        i += 1

    print("".join(s))

# Driver Code
if __name__ == '__main__':
    s = "$Gee*k;s..fo, r'Ge^eks?"
    s = [i for i in s]
    removeSpecialCharacter(s)

# This code is contributed by Mohit Kumar

C#

// C# program to remove all the characters
// other than alphabets
using System;

class GFG {

    // function to remove characters and
    // print new string
    static void removeSpecialCharacter(string s)
    {
        for (int i = 0; i < s.Length; i++)
        {

            // Finding the character whose
            // ASCII value fall under this
            // range
            if (s[i] < 'A' || s[i] > 'Z' &&
                    s[i] < 'a' || s[i] > 'z')
            {

                // erase function to erase
                // the character
                s = s.Remove(i,1);
                i--;
            }
        }

        Console.Write(s);
    }

    // Driver code
    public static void Main()
    {
        string s = "$Gee*k;s..fo, r'Ge^eks?";
        removeSpecialCharacter(s);
    }
}

// This code is contributed by Sam007.

Javascript

<script>
// Javascript program to remove all the characters
// other than alphabets

    // function to remove characters and
    // print new string
   function removeSpecialCharacter(s)
   {
       for (let i = 0; i < s.length; i++)
        {

            // Finding the character whose
            // ASCII value fall under this
            // range
            if (s[i] < 'A' || s[i] > 'Z' &&
                    s[i] < 'a' || s[i] > 'z')
            {

                // erase function to erase
                // the character
                s = s.substring(0, i) + s.substring(i + 1);
                i--;
            }
        }
        document.write(s);
   }

   // Driver code
   let s = "$Gee*k;s..fo, r'Ge^eks?";
   removeSpecialCharacter(s);



// This code is contributed by unknown2108
</script>

Output

GeeksforGeeks

Time complexity: O(N²) as erase() may take O(n) in the worst case. We can optimize the solution by keeping track of two indexes. 
Auxiliary Space: O(1)

Implementation:

C++

// CPP program to remove all the
// characters other than alphabets
#include <bits/stdc++.h>
using namespace std;

// function to remove characters and
// print new string
void removeSpecialCharacter(string s)
{
    int j = 0;
    for (int i = 0; i < s.size(); i++) {

        // Store only valid characters
        if ((s[i] >= 'A' && s[i] <= 'Z') ||
            (s[i] >='a' && s[i] <= 'z'))
        {
            s[j] = s[i];
            j++;
        }
    }
    cout << s.substr(0, j);
}

// driver code
int main()
{
    string s = "$Gee*k;s..fo, r'Ge^eks?";
    removeSpecialCharacter(s);
    return 0;
}

Java

// Java program to remove all the
// characters other than alphabets

class GFG {

// function to remove characters and
// print new string
    static void removeSpecialCharacter(String str) {
        char[] s = str.toCharArray();
        int j = 0;
        for (int i = 0; i < s.length; i++) {

            // Store only valid characters
            if ((s[i] >= 'A' && s[i] <= 'Z')
                    || (s[i] >= 'a' && s[i] <= 'z')) {
                s[j] = s[i];
                j++;
            }
        }
        System.out.println(String.valueOf(s).substring(0, j));
    }

// driver code
    public static void main(String[] args) {
        String s = "$Gee*k;s..fo, r'Ge^eks?";
        removeSpecialCharacter(s);
    }
}

// This code is contributed by 29AjayKumar

Python3

# Python program to remove all the
# characters other than alphabets

# Function to remove special characters
# and store it in another variable
def removeSpecialCharacter(s):
    t = ""
    for i in s:

        # Store only valid characters
        if (i >= 'A' and i <= 'Z') or (i >= 'a' and i <= 'z'):
            t += i
    print(t)

# Driver code
s = "$Gee*k;s..fo, r'Ge^eks?"
removeSpecialCharacter(s)

# This code is contributed by code_freak

C#

// C# program to remove all the
// characters other than alphabets
using System;
public class GFG {

// function to remove characters and
// print new string
    static void removeSpecialCharacter(String str) {
        char[] s = str.ToCharArray();
        int j = 0;
        for (int i = 0; i < s.Length; i++) {

            // Store only valid characters
            if ((s[i] >= 'A' && s[i] <= 'Z')
                    || (s[i] >= 'a' && s[i] <= 'z')) {
                s[j] = s[i];
                j++;
            }
        }
        Console.WriteLine(String.Join("",s).Substring(0, j));
    }

// driver code
    public static void Main() {
        String s = "$Gee*k;s..fo, r'Ge^eks?";
        removeSpecialCharacter(s);
    }
}
 //This code is contributed by PrinciRaj1992

Javascript

<script>

// JavaScript program to remove all the
// characters other than alphabets

// function to remove characters and
// print new string
function removeSpecialCharacter(str)
{
    let s = str.split("");
        let j = 0;
        for (let i = 0; i < s.length; i++) {

            // Store only valid characters
            if ((s[i] >= 'A' && s[i] <= 'Z')
                    || (s[i] >= 'a' && s[i] <= 'z')) {
                s[j] = s[i];
                j++;
            }
        }
        document.write((s).join("").substring(0, j));
}

// driver code
let s = "$Gee*k;s..fo, r'Ge^eks?";
removeSpecialCharacter(s);


// This code is contributed by rag2127

</script>

Output

GeeksforGeeks

Time Complexity: O(n) 
Auxiliary Space: O(1)

Approach : Using isalpha() method:

Iterate over the characters of the string and if the character is an alphabet then add the character to the new string. Finally, the new string contains only the alphabets of the given string.

Implementation:

C++

// CPP program to remove all the
// characters other than alphabets
#include <bits/stdc++.h>
using namespace std;

// function to remove characters and
// print new string
void removeSpecialCharacter(string s)
{
    // Initialize an empty string
    string ans = "";
    for (auto ch : s) {
        // if the current character
        // is an alphabet
        if (isalpha(ch))
            ans += ch;
    }
    cout << ans;
}

// driver code
int main()
{
    string s = "$Gee*k;s..fo, r'Ge^eks?";
    removeSpecialCharacter(s);
    return 0;
}

// this code is contributed by Rajdeep Mallick(rajdeep999)

Java

public class Main {
    // function to remove characters and print new string
    static void removeSpecialCharacter(String s) {
        // Initialize an empty string
        String ans = "";
        for (char ch : s.toCharArray()) {
            // if the current character is an alphabet
            if (Character.isLetter(ch))
                ans += ch;
        }
        System.out.println(ans);
    }

    // driver code
    public static void main(String[] args) {
        String s = "$Gee*k;s..fo, r'Ge^eks?";
        removeSpecialCharacter(s);
    }
}

Python3

# Python program to remove all the
# characters other than alphabets

# Function to remove special characters
# and store it in another variable
def removeSpecialCharacter(s):
    t = ""
    for i in s:
        if(i.isalpha()):
            t+=i
    print(t)
s = "$Gee*k;s..fo, r'Ge^eks?"
removeSpecialCharacter(s)

C#

using System;

public class Program {
    public static void Main()
    {
        string s = "$Gee*k;s..fo, r'Ge^eks?";
        RemoveSpecialCharacter(s);
    }

    // function to remove characters and print new string
    public static void RemoveSpecialCharacter(string s)
    {
        // Initialize an empty string
        string ans = "";
        foreach(char ch in s)
        {
            // if the current character is an alphabet
            if (Char.IsLetter(ch))
                ans += ch;
        }
        Console.WriteLine(ans);
    }
}

// This code is contributed by sarojmcy2e

Javascript

// function to remove characters and print new string
function removeSpecialCharacter(s) {
  // Initialize an empty string
  let ans = "";
  for (let i = 0; i < s.length; i++) {
    // if the current character is an alphabet
    if (/[a-zA-Z]/.test(s[i])) {
      ans += s[i];
    }
  }
  console.log(ans);
}

// driver code
let s = "$Gee*k;s..fo, r'Ge^eks?";
removeSpecialCharacter(s);

// This code is contributed by princekumaras

Output

GeeksforGeeks

Time Complexity: O(n) 
Auxiliary Space: O(n)

Approach: Without built-in methods.

Initialize an empty string, string with lowercase alphabets(la) and uppercase alphabets(ua). Iterate a for loop on string,  if the character is in la or ua using in and not in operators concatenate them to an empty string. Display the string after the end of the loop.

Implementation:

C++

// C++ program to remove all the
// characters other than alphabets
#include<bits/stdc++.h>
using namespace std;
string removeSpecialCharacter(string s) {
  string t = "";
  string la = "abcdefghijklmnopqrstuvwxyz";
  string ua = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  for (int i = 0; i < s.length(); i++) {
    if(la.find(s[i]) != string::npos ||
       ua.find(s[i]) != string::npos)
    {
      t += s[i];
    }
  }
  cout << t << endl;
  return t;
}
int main() {
  string s = "$Gee*k;s..fo, r'Ge^eks?";
  removeSpecialCharacter(s);
  return 0;
}

// This code is contributed by shivamsharma215

Java

// Java program to remove all the
// characters other than alphabets
import java.util.*;

class Gfg {
    static String removeSpecialCharacter(String s)
    {
        // empty string to store the result
        String t = "";
        String la = "abcdefghijklmnopqrstuvwxyz";
        String ua = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        for (int i = 0; i < s.length(); i++) {

          // if it is a letter, add it to the result string
            if (la.contains(String.valueOf(s.charAt(i)))
                || ua.contains(
                    String.valueOf(s.charAt(i)))) {
                t += s.charAt(i);
            }
        }
        System.out.println(t);
        return t;
    }

    // Driver Code
    public static void main(String[] args)
    {
        String s = "$Gee*k;s..fo, r'Ge^eks?";
        removeSpecialCharacter(s);
    }
}

Python3

# Python program to remove all the
# characters other than alphabets

# Function to remove special characters
# and store it in another variable
def removeSpecialCharacter(s):
    t = ""
    la="abcdefghijklmnopqrstuvwxyz"
    ua="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    for i in s:
        if(i in la or i in ua):
            t+=i
    print(t)
s = "$Gee*k;s..fo, r'Ge^eks?"
removeSpecialCharacter(s)

C#

// C# program to remove all the
// characters other than alphabets
using System;

class Gfg{
    static string removeSpecialCharacter(string s)
    {
        string t = "";
        string la = "abcdefghijklmnopqrstuvwxyz";
        string ua = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        for (int i = 0; i < s.Length; i++)
            if(la.Contains(s[i]) || ua.Contains(s[i]))
                t += s[i];

        Console.WriteLine(t);
        return t;
    }
    public static void Main()
    {
      string s = "$Gee*k;s..fo, r'Ge^eks?";
      removeSpecialCharacter(s);
    }
}

Javascript

// JS program to remove all the
// characters other than alphabets
function removeSpecialCharacter( s) {
  let t = "";
  let la = "abcdefghijklmnopqrstuvwxyz";
  let ua = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  for (let i = 0; i < s.length; i++)
  {
    if(la.includes(s[i]) || ua.includes(s[i]))
    {
      t += s[i];
    }
  }
  console.log(t);
  return t;
}
let s = "$Gee*k;s..fo, r'Ge^eks?";
removeSpecialCharacter(s);

// this code is contributed by poojaagarwal2.

Output

GeeksforGeeks

Time complexity: O(n), where n is the length of the input string s. This is because in the worst case, the loop in the removeSpecialCharacter function will have to iterate through all the characters in the string.
Auxiliary Space: O(n), where n is the length of the final string without special characters. This is because the function creates a new string t to store only the alphabetic characters. The size of the string t will be at most equal to the size of the original string s.

Approach: Using ord() function.The ASCII value of the lowercase alphabet is from 97 to 122. And, the ASCII value of the uppercase alphabet is from 65 to 90.

C++

#include <bits/stdc++.h>
using namespace std;

// Function to remove special characters
// and store it in another variable
void removeSpecialCharacter(string s)
{
    string t = "";
    for (int i = 0; i < s.length(); i++) {
        if ((s[i] >= 'a' && s[i] <= 'z') || (s[i] >= 'A' && s[i] <= 'Z')) {
            t += s[i];
        }
    }
    cout << t << endl;
}

int main()
{
    string s = "$Gee*k;s..fo, r'Ge^eks?";
    removeSpecialCharacter(s);
    return 0;
}

Java

import java.util.*;

class GFG {
    // Function to remove special characters
    // and store it in another variable
    static void removeSpecialCharacter(String s) {
        String t = "";
        for (int i = 0; i < s.length(); i++) {
            if ((s.charAt(i) >= 'a' && s.charAt(i) <= 'z') || (s.charAt(i) >= 'A' && s.charAt(i) <= 'Z')) {
                t += s.charAt(i);
            }
        }
        System.out.println(t);
    }

    public static void main(String[] args) {
        String s = "$Gee*k;s..fo, r'Ge^eks?";
        removeSpecialCharacter(s);
    }
}

Python3

# Python program to remove all the
# characters other than alphabets

# Function to remove special characters
# and store it in another variable
def removeSpecialCharacter(s):
    t = ""
    for i in s:
        if(ord(i) in range(97,123) or ord(i) in range(65,91)):
            t+=i
    print(t)
s = "$Gee*k;s..fo, r'Ge^eks?"
removeSpecialCharacter(s)

C#

using System;

class GFG {
    // Function to remove special characters
    // and store it in another variable
    static void RemoveSpecialCharacter(string s)
    {
        string t = "";
        for (int i = 0; i < s.Length; i++) {
            // Check if the character is an alphabet
            // (lowercase or uppercase)
            if ((s[i] >= 'a' && s[i] <= 'z')
                || (s[i] >= 'A' && s[i] <= 'Z')) {
                t += s[i];
            }
        }
        Console.WriteLine(t);
    }

    static void Main(string[] args)
    {
        string s = "$Gee*k;s..fo, r'Ge^eks?";
        RemoveSpecialCharacter(s);
    }
}

Javascript

// JavaScript program to remove all the
// characters other than alphabets

// Function to remove special characters
// and store it in another variable
function removeSpecialCharacter(s)
{
    let t = ""
    for (let i=0; i<s.length; i++)
        if((s[i]>='a' && s[i]<='z') || (s[i]>='A' && s[i]<='Z'))
            t+=s[i];
    console.log(t);
}
let s = "$Gee*k;s..fo, r'Ge^eks?";
removeSpecialCharacter(s);

Output

GeeksforGeeks

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