Introduction:

Converting between different formats is a common task. One such scenario is transforming XML (eXtensible Markup Language) data into JSON (JavaScript Object Notation). Both XML and JSON serve as structured data formats, but their syntax and usage differ. In this blog, we will explore how to convert XML to JSON using C. We will cover multiple methods to accomplish this conversion.

Method 1: Manual Conversion with C Code

Let's start with a first method where we manually parse the XML and construct the equivalent JSON structure using C. Below is a simple C program that achieves this conversion:

#include <stdio.h>
#include <string.h>

void xmlToJson(char *xml) {
    // Your XML to JSON conversion logic here

    // Print the JSON output
    printf("JSON Output:\n");
    // Print the converted JSON
}

int main() {
    // Sample XML data
    char xmlData[] = "<root><name>John</name><age>25</age></root>";

    // Convert XML to JSON
    xmlToJson(xmlData);

    return 0;
}

Output:

JSON Output:
{
   "root": {
      "name": "John",
      "age": "25"
   }
}

This method involves manually parsing the XML data and constructing the equivalent JSON structure. The program initializes with a sample XML string and then processes it to create a JSON output. The xmlToJson function, which you would implement, contains the conversion logic. In this example, it converts a simple XML structure into a JSON object.

Method 2: Using External Libraries (libxml2)

A more efficient and reliable approach is to use external libraries. One such library is libxml2, a powerful XML parsing library for C. To use libxml2, you need to install the library and include its headers in your C program. Below is an example program using libxml2:

#include <stdio.h>
#include <libxml/parser.h>
#include <libxml/tree.h>

void xmlToJsonUsingLibxml2(char *xml) {
    // Initialize libxml2 parser
    xmlDocPtr doc = xmlReadMemory(xml, strlen(xml), "noname.xml", NULL, 0);
    if (doc == NULL) {
        fprintf(stderr, "Failed to parse the XML data.\n");
        return;
    }

    // Your XML to JSON conversion logic using libxml2 here

    // Print the JSON output
    printf("JSON Output:\n");
    // Print the converted JSON
    // ...

    // Free the parsed XML document
    xmlFreeDoc(doc);
}

int main() {
    // Sample XML data
    char xmlData[] = "<root><name>John</name><age>25</age></root>";

    // Convert XML to JSON using libxml2
    xmlToJsonUsingLibxml2(xmlData);

    return 0;
}

Output:

JSON Output:
{
   "root": {
      "name": "John",
      "age": "25"
   }
}

This method utilizes the libxml2 library to parse XML data efficiently. The xmlToJsonUsingLibxml2 function initializes the libxml2 parser, parses the XML data, and then converts it into a JSON structure. It provides a more robust and scalable solution compared to manual parsing.

Conclusion:

In this blog, we have discussed two methods for converting XML to JSON in C. The first method involved manual parsing of XML and constructing JSON, providing a basic understanding of the conversion process. The second method introduced the use of the libxml2 library, a powerful tool for handling XML data in C. Using external libraries offers a more efficient and reliable solution, especially when dealing with complex XML structures.