Working with XML

How to:

C doesn’t have built-in support for XML, so you’ll need to use external libraries. One popular choice is libxml2, a stable and feature-rich library. Here’s how to read and parse an XML file using libxml2.

First, ensure you have libxml2 installed on your system. You may need to install it through your package manager (e.g., apt-get install libxml2-dev on Debian systems).

Next, include the libxml2 header in your C program:

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

Now, let’s write a simple program to parse an XML file and print out the names of the first-level elements:

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

int main(void) {
    xmlDoc *document = NULL;
    xmlNode *root_element = NULL;

    // Initialize the library and check potential ABI mismatches

    // Parse the file and get the DOM
    document = xmlReadFile("your_file.xml", NULL, 0);

    if (document == NULL) {
        printf("Failed to parse the XML file\n");
        return -1;

    //Get the root element node
    root_element = xmlDocGetRootElement(document);

    for (xmlNode *currentNode = root_element; currentNode; currentNode = currentNode->next) {
        if (currentNode->type == XML_ELEMENT_NODE) {
            printf("Node Type: Element, name: %s\n", currentNode->name);

    // Freeing the memory allocated for the parser and the DOM

    // Cleanup and check leaks
    xmlMemoryDump(); // Optional

    return 0;

To compile this program, make sure to link against libxml2:

gcc -o xml_example xml_example.c $(xml2-config --cflags --libs)

Assuming you have an XML file named your_file.xml, running the compiled program should print the names of its first-level elements.

Deep Dive

The interaction between C and XML is a tale of bringing together two vastly different worlds: the structured, byte-level, procedural paradigm of C and the hierarchical, verbose, and document-centric model of XML. When integrating XML handling capabilities into C programs, developers leverage the strengths of C - such as speed and low-level memory access - to efficiently parse and manipulate XML documents.

libxml2, developed as part of the GNOME project, emerged as the de facto standard for XML processing in C due to its comprehensive support for XML standards and its performance. It embodies years of development effort and community contributions, making it robust and efficient for most XML tasks.

While libxml2 offers powerful capabilities, it’s worth noting that the complexity of XML parsing and manipulation can introduce significant overhead. In scenarios where XML’s verbosity and complexity are unjustifiable, alternatives like JSON might be preferable for data interchange. Nevertheless, for XML-centric applications or environments where XML use is entrenched, mastering libxml2 usage in C unlocks the ability to work with a wide range of XML documents and APIs, bridging the gap between the C programming language and the world of structured document processing.