Split string into key-value pairs using C++

Introduction:

In the realm of programming, the ability to parse strings efficiently is a valuable skill. It becomes particularly crucial when dealing with data in the form of key-value pairs. While there are libraries available for this task, let's explore a minimalistic approach using C++ without relying on external libraries.

The Challenge:

Consider a string `s` containing key-value pairs, where keys and values are separated by colons, and different pairs are delimited by commas. The goal is to extract and store these pairs without resorting to external libraries, showcasing a straightforward yet efficient solution.

The Code Breakdown:

#include <iostream>

#include <cstring>

#include <unordered_map>

using namespace std;

int main(int arg, char **argv)

{

    string s = "key1:value1,key2:value2,key3:value3,";

    unordered_map<string, string> kv;

    bool k = false; // Flag to switch between keys and values

    string key, value;

    for (int i = 0; i < s.length(); i++)

    {

        if (s.at(i) == ':')

            k = true;

        else if (s.at(i) == ',')

        {

            kv[key] = value; // Store key-value pair in the unordered_map

            key = "";

            value = "";

            k = false;

        }

        else if (!k)

            key += s[i];

        else

            value += s[i];

    }

    cout << "Value for key1: " << kv["key1"] << '\n';

    return 0;

}

Explanation:

1. Parsing Logic: The code iterates through each character in the string `s` and determines whether it is a key or a value based on the presence of colons (`:`) and commas (`,`).

2. Storage:  Key-value pairs are stored in an `unordered_map` named `kv`. This data structure is advantageous due to its internal implementation as a hash table, providing fast access, insertion, and deletion.

3. Efficiency:  By avoiding external libraries, the code remains lightweight and focused on the specific task of string parsing. The use of simple boolean flags (`k`) aids in distinguishing between keys and values during the parsing process.

4. Output : The program concludes by demonstrating the retrieval of the value associated with "key1" from the unordered_map, showcasing the effectiveness of the parsing logic.

Conclusion:

In this compact C++ program, we've successfully tackled the challenge of extracting key-value pairs from a string without relying on external libraries. The use of fundamental string manipulation and the unordered_map data structure highlights the elegance of a minimalistic approach to string parsing, ensuring efficiency without unnecessary dependencies. This solution serves as a foundation for developers seeking a lightweight and effective method for handling key-value pairs within strings.