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Python | Find Sum of all Numbers & Digits in an Alpha-Numeric String

Posted in Programming   LAST UPDATED: AUGUST 16, 2021

    Hello Everyone, in this tutorial we are going to write a simple program in python to calculate the sum of all numbers and digits in an alpha-numeric string.

    Sum of all numbers in a alpha numeric string

    Recently, I attend an interview on our campus. In the interview, the interviewer asked me to solve this problem.

    This is a very simple problem, just the basics of a language are enough for one to solve this problem.

    Algorithm to solve the problem:

    1. Take the string input from the user and store it in variable n.

    2. Initialize sum = 0, temp_num = 0

    3. Now loop through all characters in that string.

    4. If it is an alphabet, ignore it

    5. If it is a numeric value, append it to variable temp_num until the next character is an alphabet and add temp_num to the sum.

    6. Finally, print the sum at the end of the program. Thus gives the sum of all numbers in an alpha-numeric string.

    1. Code for Sum of all Numbers in Alpha-Numeric String

    Let's see how we can find the sum of numbers in alpha numeric string. So for example the string is s1s22s33, then numbers are 1, 22 and 33.

    #1. Without Recursion

    n = input("Enter an Alpha-Numeric String: ")
    n_sum = 0
    temp_num = ""
    for i in n: 
        if( i.isalpha() ):
            if( temp_num != "" ):
                n_sum = n_sum + int(temp_num)
                temp_num = 0
        else:
            temp_num = str(temp_num) + str(i)
            
    if( temp_num != "" ):
        n_sum = n_sum + int(temp_num)
        temp_num = 0
            
    print(n_sum)


    Enter an Alpha-Numeric String: s1s22s33
    56

    #2. With Recursion

    Now we will see another way of implementing this, using recursion.

    def sumOfNumbers(string, n, temp, sums):
        
        curr_val = string[n]
    
        if( curr_val.isalpha() ):
            sums = sums + int(temp)
            temp = 0
        else:
            temp = str(temp) + str(curr_val)
            
        if n == 0:
            return sums
        else:
            return sumOfNumbers(string, n-1, temp, sums)
    
    string = input("Enter a Alpha Numeric String: ")
    n = len(string) - 1
    print( sumOfNumbers(string, n, temp=0, sums=0) )


    Enter an Alpha-Numeric String: study24tonight77
    101

    2. Code for Sum of all Digits In Alpha-Numberic String

    Here the algorithm is very simple, just add the value to the sum only if it is a numeric value and finally print sum. In this case, for string s1s22s33, digits are 1, 2, 2, 3 and 3.

    #1 Without Recursion

    string = input("Enter a Alpha-Numeric String: ")
    sums = 0
    for i in string:
        if( i.isnumeric() ):
            sums = sums+int(i)
    print(sums)


    Enter an Alpha-Numeric String: a11s22s55
    16

    #2 Using Recursion

    def sumOfNumbers(string, n, sums):
        
        curr_val = string[n]
        if( curr_val.isnumeric() ):
            sums = sums + int(curr_val)
            
        if n == 0:
            return sums
        else:
            return sumOfNumbers(string, n-1, sums)
    
    string = input("Enter a Alpha Numeric String: ")
    n = len(string) - 1
    print( sumOfNumbers(string, n, sums=0) )
    


    Enter an Alpha-Numeric String: study24tonight77
    20

    Conclusion:

    Pheww! This is a brief explanation of how to find the sum of all numbers and digits in an alpha-numeric string in python. I hope that you enjoyed the post. If you feel that this post is useful, please share it with your friends and colleagues.

    Thanks for reading it till the end.

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    Published by: vineelpynam
    Tags:PythonAlgorithm
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