Compare two alphanumeric string in python

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Given two strings that can contain lower and uppercase alphabets, numbers and special characters like dots, blank spaces, commas, etc. Compare both strings considering only alphanumeric characters([a-b], [A-B] and [0-9]) if they are equal or not. For example, strings “Ram, Shyam” and “Ram-Shyam” both are the same and also “/.’;[]” and “@# >” are same.

Examples: 

Input: str1 = "Ram, Shyam", str2 = " Ram - Shyam."
Output: Equal
Explanation: 
if we ignore all characters 
except alphanumeric characters 
then strings will be, 
str1 = "RamShyam" and str2 = "RamShyam". 
Therefore both strings are equal.

Input : str1 = "aaa123", str2 = "@aaa-12-3"
Output : Equal

Input : str1 = "abc123", str2 = "123abc"
Output : Unequal
Explanation: 
In this, str1 = "abc123" and str2 = "123abc". 
Therefore both strings are not equal.

Since we have to compare only alphanumeric characters therefore whenever any other character is found simply ignore it by increasing iterator pointer. For doing it simply take two integer variables i and j and initialize them by 0. Now run a loop to compare each and every character of both strings. Compare one by one if the character is alphanumeric otherwise increase the value of i or j by one.

Below is the implementation of the above approach:  

C++

#include

using namespace std;

bool CompareAlphanumeric(string& str1, string& str2)

{

    int i, j;

    i = 0;

    j = 0;

    int len1 = str1.size();

    int len2 = str2.size();

    while (i <= len1 && j <= len2) {

        while (i < len1

               && (!((str1[i] >= 'a' && str1[i] <= 'z')

                     || (str1[i] >= 'A' && str1[i] <= 'Z')

                     || (str1[i] >= '0' && str1[i] <= '9')))) {

            i++;

        }

        while (j < len2

               && (!((str2[j] >= 'a' && str2[j] <= 'z')

                     || (str2[j] >= 'A' && str2[j] <= 'Z')

                     || (str2[j] >= '0' && str2[j] <= '9')))) {

            j++;

        }

        if (i == len1 && j == len2)

            return true;

        else if (str1[i] != str2[j])

            return false;

        else {

            i++;

            j++;

        }

    }

    return false;

}

void CompareAlphanumericUtil(string str1, string str2)

{

    bool res;

    res = CompareAlphanumeric(str1, str2);

    if (res == true)

        cout << "Equal" << endl;

    else

        cout << "Unequal" << endl;

}

int main()

{

    string str1, str2;

    str1 = "Ram, Shyam";

    str2 = " Ram - Shyam.";

    CompareAlphanumericUtil(str1, str2);

    str1 = "abc123";

    str2 = "123abc";

    CompareAlphanumericUtil(str1, str2);

    return 0;

}

Java

import java.util.*;

class GFG

{

static boolean CompareAlphanumeric(char[] str1,

                                   char[] str2)

{

    int i, j;

    i = 0;

    j = 0;

    int len1 = str1.length;

    int len2 = str2.length;

    while (i <= len1 && j <= len2)

    {

        while (i < len1 && (!((str1[i] >= 'a' && str1[i] <= 'z') ||

                              (str1[i] >= 'A' && str1[i] <= 'Z') ||

                              (str1[i] >= '0' && str1[i] <= '9'))))

        {

            i++;

        }

        while (j < len2 && (!((str2[j] >= 'a' && str2[j] <= 'z') ||

                              (str2[j] >= 'A' && str2[j] <= 'Z') ||

                              (str2[j] >= '0' && str2[j] <= '9'))))

        {

            j++;

        }

        if (i == len1 && j == len2)

        {

            return true;

        }

        else if (str1[i] != str2[j])

        {

            return false;

        }

        else

        {

            i++;

            j++;

        }

    }

    return false;

}

static void CompareAlphanumericUtil(String str1,

                                    String str2)

{

    boolean res;

    res = CompareAlphanumeric(str1.toCharArray(),

                              str2.toCharArray());

    if (res == true)

    {

        System.out.println("Equal");

    }

    else

    {

        System.out.println("Unequal");

    }

}

public static void main(String[] args)

{

    String str1, str2;

    str1 = "Ram, Shyam";

    str2 = " Ram - Shyam.";

    CompareAlphanumericUtil(str1, str2);

    str1 = "abc123";

    str2 = "123abc";

    CompareAlphanumericUtil(str1, str2);

}

}

Python3

def CompareAlphanumeric(str1, str2):

    i = 0

    j = 0

    len1 = len(str1)

    len2 = len(str2)

    while (i <= len1 and j <= len2):

        while (i < len1 and

              (((str1[i] >= 'a' and str1[i] <= 'z') or

                (str1[i] >= 'A' and str1[i] <= 'Z') or

                (str1[i] >= '0' and str1[i] <= '9')) == False)):

            i += 1

        while (j < len2 and

              (((str2[j] >= 'a' and str2[j] <= 'z') or

                (str2[j] >= 'A' and str2[j] <= 'Z') or

                (str2[j] >= '0' and str2[j] <= '9')) == False)):

            j += 1

        if (i == len1 and j == len2):

            return True

        elif (str1[i] != str2[j]):

            return False

        else:

            i += 1

            j += 1

    return False

def CompareAlphanumericUtil(str1, str2):

    res = CompareAlphanumeric(str1, str2)

    if (res == True):

        print("Equal")

    else:

        print("Unequal")

if __name__ == '__main__':

    str1 = "Ram, Shyam"

    str2 = " Ram - Shyam."

    CompareAlphanumericUtil(str1, str2)

    str1 = "abc123"

    str2 = "123abc"

    CompareAlphanumericUtil(str1, str2)

C#

using System;

class GFG

{

    static bool CompareAlphanumeric(char []str1,

                                    char []str2)

    {

        int i, j;

        i = 0;

        j = 0;

        int len1 = str1.Length;

        int len2 = str2.Length;

        while (i <= len1 && j <= len2)

        {

            while (i < len1 && (!((str1[i] >= 'a' && str1[i] <= 'z') ||

                                  (str1[i] >= 'A' && str1[i] <= 'Z') ||

                                  (str1[i] >= '0' && str1[i] <= '9'))))

            {

                i++;

            }

            while (j < len2 && (!((str2[j] >= 'a' && str2[j] <= 'z') ||

                                  (str2[j] >= 'A' && str2[j] <= 'Z') ||

                                  (str2[j] >= '0' && str2[j] <= '9'))))

            {

                j++;

            }

            if (i == len1 && j == len2)

            {

                return true;

            }

            else if (str1[i] != str2[j])

            {

                return false;

            }

            else

            {

                i++;

                j++;

            }

        }

        return false;

    }

    static void CompareAlphanumericUtil(string str1,

                                        string str2)

    {

        bool res;

        res = CompareAlphanumeric(str1.ToCharArray(),

                                  str2.ToCharArray());

        if (res == true)

        {

            Console.WriteLine("Equal");

        }

        else

        {

            Console.WriteLine("Unequal");

        }

    }

    public static void Main()

    {

        string str1, str2;

        str1 = "Ram, Shyam";

        str2 = " Ram - Shyam.";

        CompareAlphanumericUtil(str1, str2);

        str1 = "abc123";

        str2 = "123abc";

        CompareAlphanumericUtil(str1, str2);

    }

}

Javascript

Time Complexity: O(n*n)
Auxiliary Space: O(1), as no extra space is required