Http Client in C++

Here’s the translation of the Go HTTP client example to C++, formatted in Markdown suitable for Hugo:

The C++ standard library doesn’t come with built-in HTTP client functionality, so we’ll use the popular libcurl library for this example. Make sure you have libcurl installed and properly linked to your project.

#include <iostream>
#include <curl/curl.h>
#include <sstream>
#include <string>

// Callback function to handle the response
size_t WriteCallback(void* contents, size_t size, size_t nmemb, std::string* output) {
    size_t total_size = size * nmemb;
    output->append((char*)contents, total_size);
    return total_size;
}

int main() {
    // Initialize libcurl
    CURL* curl = curl_easy_init();
    if (!curl) {
        std::cerr << "Failed to initialize libcurl" << std::endl;
        return 1;
    }

    // Set the URL
    curl_easy_setopt(curl, CURLOPT_URL, "https://gobyexample.com");

    // Set up the response handling
    std::string response_string;
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response_string);

    // Perform the request
    CURLcode res = curl_easy_perform(curl);
    if (res != CURLE_OK) {
        std::cerr << "curl_easy_perform() failed: " << curl_easy_strerror(res) << std::endl;
        curl_easy_cleanup(curl);
        return 1;
    }

    // Get the response status
    long response_code;
    curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &response_code);
    std::cout << "Response status: " << response_code << std::endl;

    // Print the first 5 lines of the response body
    std::istringstream response_stream(response_string);
    std::string line;
    for (int i = 0; i < 5 && std::getline(response_stream, line); ++i) {
        std::cout << line << std::endl;
    }

    // Clean up
    curl_easy_cleanup(curl);

    return 0;
}

This C++ program uses libcurl to issue an HTTP GET request to a server. Here’s a breakdown of what the code does:

We include the necessary headers, including curl/curl.h for libcurl.
We define a WriteCallback function that libcurl will use to handle the response data.
In the main function, we initialize libcurl with curl_easy_init().
We set the URL for the request using curl_easy_setopt().
We set up the response handling by specifying our WriteCallback function and a string to store the response.
We perform the request with curl_easy_perform().
After the request, we retrieve the response status code using curl_easy_getinfo().
We then print the response status and the first 5 lines of the response body.
Finally, we clean up the libcurl resources with curl_easy_cleanup().

To compile and run this program, you’ll need to link against libcurl. For example:

$ g++ -o http_client http_client.cpp -lcurl
$ ./http_client
Response status: 200
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Go by Example</title>

This example demonstrates how to make HTTP requests in C++ using libcurl, which provides functionality similar to the net/http package in other languages.

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Http Client in C++