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Remove all characters other than alphabets from string

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  • Difficulty Level : Easy
  • Last Updated : 10 Aug, 2022

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 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. 

Implementation:

C++




// CPP program to remove all the
// characters other then 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 then 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 then 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 then 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 then 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) 

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:

Python3




# Python program to remove all the
# characters other then 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)

Output

GeeksforGeeks

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:

Python3




# Python program to remove all the
# characters other then 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)

Output

GeeksforGeeks

This article is contributed by Prabhat Kumar Singh. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.


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