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.
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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