Sending an HTTP request

How to:

To send an HTTP request in C, you’ll generally lean on libraries like libcurl, as C does not have built-in support for web protocols. Here’s a simple example using libcurl to perform a GET request:

First, ensure you have libcurl installed on your system. Then, include the necessary headers and link against the libcurl library in your source file:

#include <stdio.h>
#include <curl/curl.h>

int main(void) {
    CURL *curl;
    CURLcode res;

    curl = curl_easy_init(); // Initialize a libcurl handle
    if(curl) {
        // Set the URL that receives the libcurl handle
        curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
        // Define a callback to get the data
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, NULL); 
        // Perform the request, res will get the return code
        res = curl_easy_perform(curl);
        // Check for errors
        if(res != CURLE_OK)
            fprintf(stderr, "curl_easy_perform() failed: %s\n",

        // Always cleanup
    return 0;

Compile this with something akin to gcc -o http_request http_request.c -lcurl, running it should perform a simple GET request to “http://example.com”.

Sample Output

Since the example doesn’t process the server’s response, running it won’t produce a visible output beyond potential error messages. Integrating the callback function for processing received data is essential for meaningful interaction.

Deep Dive

The concept of sending HTTP requests from a C program hinges on the language’s powerful networking capabilities, coupled with external libraries since C itself is a low-level language without built-in high-level internet protocol support. Historically, programmers would manually use socket programming in C, a complex and tedious process, to interact with web servers before the advent of dedicated libraries like libcurl.

Libcurl, built on top of C, streamlines the process, abstracting away the gritty details of socket programming and HTTP protocol specifics. It supports a multitude of protocols beyond HTTP/HTTPS, including FTP, SMTP, and more, making it a versatile tool for network programming in C.

While using libcurl for HTTP requests in C is practical, modern programming often gravitates towards languages with built-in support for such tasks, like Python (requests library) or JavaScript (Fetch API). These alternatives offer simpler, more readable syntax at the expense of the granular control and performance optimizations possible in C through direct socket manipulation and finely-tuned library use.

For critical performance applications or where direct system-level interaction is necessary, C remains a viable option, particularly with libcurl smoothing over the complexities of web communication. However, for most high-level web interactions, exploring more dedicated web programming languages might prove more efficient.