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Calculate sum of all numbers present in a string
  • Difficulty Level : Easy
  • Last Updated : 15 Oct, 2020
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Given a string containing alphanumeric characters, calculate sum of all numbers present in the string.

Examples: 

Input:  1abc23
Output: 24

Input:  geeks4geeks
Output: 4

Input:  1abc2x30yz67
Output: 100

Input:  123abc
Output: 123

Difficulty level: Rookie

The only tricky part in this question is that multiple consecutive digits are considered as one number.
The idea is very simple. We scan each character of the input string and if a number is formed by consecutive characters of the string, we increment the result by that amount. 

Below is the implementation of the above idea:



C++




// C++ program to calculate sum of all numbers present
// in a string containing alphanumeric characters
#include <iostream>
using namespace std;
  
// Function to calculate sum of all numbers present
// in a string containing alphanumeric characters
int findSum(string str)
{
    // A temporary string
    string temp = "";
  
    // holds sum of all numbers present in the string
    int sum = 0;
  
    // read each character in input string
    for (char ch : str) {
        // if current character is a digit
        if (isdigit(ch))
            temp += ch;
  
        // if current character is an alphabet
        else {
            // increment sum by number found earlier
            // (if any)
            sum += atoi(temp.c_str());
  
            // reset temporary string to empty
            temp = "";
        }
    }
  
    // atoi(temp.c_str()) takes care of trailing
    // numbers
    return sum + atoi(temp.c_str());
}
  
// Driver code
int main()
{
    // input alphanumeric string
    string str = "12abc20yz68";
  
    // Function call
    cout << findSum(str);
  
    return 0;
}

Java




// Java program to calculate sum of all numbers present
// in a string containing alphanumeric characters
class GFG {
  
    // Function to calculate sum of all numbers present
    // in a string containing alphanumeric characters
    static int findSum(String str)
    {
        // A temporary string
        String temp = "0";
  
        // holds sum of all numbers present in the string
        int sum = 0;
  
        // read each character in input string
        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);
  
            // if current character is a digit
            if (Character.isDigit(ch))
                temp += ch;
  
            // if current character is an alphabet
            else {
                // increment sum by number found earlier
                // (if any)
                sum += Integer.parseInt(temp);
  
                // reset temporary string to empty
                temp = "0";
            }
        }
  
        // atoi(temp.c_str()) takes care of trailing
        // numbers
        return sum + Integer.parseInt(temp);
    }
  
    // Driver code
    public static void main(String[] args)
    {
  
        // input alphanumeric string
        String str = "12abc20yz68";
  
        // Function call
        System.out.println(findSum(str));
    }
}
  
// This code is contributed by AnkitRai01

Python3




# Python3 program to calculate sum of
# all numbers present in a str1ing
# containing alphanumeric characters
  
# Function to calculate sum of all
# numbers present in a str1ing
# containing alphanumeric characters
  
  
def findSum(str1):
  
    # A temporary str1ing
    temp = "0"
  
    # holds sum of all numbers
    # present in the str1ing
    Sum = 0
  
    # read each character in input string
    for ch in str1:
  
        # if current character is a digit
        if (ch.isdigit()):
            temp += ch
  
        # if current character is an alphabet
        else:
  
            # increment Sum by number found
            # earlier(if any)
            Sum += int(temp)
  
            # reset temporary str1ing to empty
            temp = "0"
  
    # atoi(temp.c_str1()) takes care
    # of trailing numbers
    return Sum + int(temp)
  
# Driver code
  
  
# input alphanumeric str1ing
str1 = "12abc20yz68"
  
# Function call
print(findSum(str1))
  
# This code is contributed
# by mohit kumar

C#




// C# program to calculate sum of
// all numbers present in a string
// containing alphanumeric characters
using System;
  
class GFG {
  
    // Function to calculate sum of
    // all numbers present in a string
    // containing alphanumeric characters
    static int findSum(String str)
    {
        // A temporary string
        String temp = "0";
  
        // holds sum of all numbers
        // present in the string
        int sum = 0;
  
        // read each character in input string
        for (int i = 0; i < str.Length; i++) {
            char ch = str[i];
  
            // if current character is a digit
            if (char.IsDigit(ch))
                temp += ch;
  
            // if current character is an alphabet
            else {
  
                // increment sum by number found earlier
                // (if any)
                sum += int.Parse(temp);
  
                // reset temporary string to empty
                temp = "0";
            }
        }
  
        // atoi(temp.c_str()) takes care of trailing
        // numbers
        return sum + int.Parse(temp);
    }
  
    // Driver code
    public static void Main(String[] args)
    {
  
        // input alphanumeric string
        String str = "12abc20yz68";
  
        // Function call
        Console.WriteLine(findSum(str));
    }
}
  
// This code is contributed by PrinciRaj1992
Output
100

Time complexity: O(n) where n is length of the string.

A Better Solution implementing Regex.

Python3




# Python3 program to calculate sum of
# all numbers present in a str1ing
# containing alphanumeric characters
  
# Function to calculate sum of all
# numbers present in a str1ing
# containing alphanumeric characters
import re
  
  
def find_sum(str1):
    # Regular Expression that matches
    # digits in between a string
    return sum(map(int, re.findall('\d+', str1)))
  
# Driver code
# input alphanumeric str1ing
str1 = "12abc20yz68"
  
# Function call
print(find_sum(str1))
  
# This code is contributed
# by Venkata Ramana B
Output
100

This article is contributed by Aditya Goel. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
 

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