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Install and Link libcurl

Write the HTTP GET Request Code

Compile and Run

Handle Errors and Timeouts (Optional)

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如何用 C 語(yǔ)言發(fā)出 HTTP GET 請(qǐng)求

Alexander

Oct 13, 2025 am 01:12 AM

使用libcurl庫(kù)可實(shí)現(xiàn)C 中的HTTP GET請(qǐng)求，需先安裝并鏈接libcurl，然后通過(guò)curl_easy_init初始化、設(shè)置URL和回調(diào)函數(shù)接收數(shù)據(jù)、執(zhí)行請(qǐng)求并清理資源，最后編譯時(shí)鏈接-lcurl。

How to make an HTTP GET request in C

Making an HTTP GET request in C requires using a networking library, since the standard C library doesn't include built-in support for HTTP. One of the most common and practical ways is using libcurl, a powerful, cross-platform library for handling URLs and HTTP requests.

Install and Link libcurl

Before writing code, make sure libcurl is installed on your system.

Ubuntu/Debian: sudo apt install libcurl4-openssl-dev
macOS (with Homebrew): brew install curl
Windows: Use vcpkg or download prebuilt binaries.

When compiling, link against the curl library using -lcurl.

Write the HTTP GET Request Code

Here’s a simple example that performs an HTTP GET request and prints the response body:

#include <iostream>
#include <string>
#include <curl/curl.h>
<p>// Callback function to handle data received
size_t WriteCallback(void<em> contents, size_t size, size_t nmemb, std::string</em> output) {
size_t totalSize = size <em> nmemb;
output->append((char</em>)contents, totalSize);
return totalSize;
}</p><p>int main() {
CURL* curl;
CURLcode res;
std::string readBuffer;</p><pre class="brush:php;toolbar:false"><code>curl = curl_easy_init();
if (curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://httpbin.org/get");
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &readBuffer);

    res = curl_easy_perform(curl);

    if (res == CURLE_OK) {
        std::cout << "Response:\n" << readBuffer << std::endl;
    } else {
        std::cerr << "Request failed: " << curl_easy_strerror(res) << std::endl;
    }

    curl_easy_cleanup(curl);
} else {
    std::cerr << "Could not initialize curl." << std::endl;
}

return 0;

}

Compile and Run

Save the code to a file (e.g., get_request.cpp) and compile it:

g get_request.cpp -o get_request -lcurl

Then run:

./get_request

Handle Errors and Timeouts (Optional)

You can improve reliability by setting timeouts and checking connection issues:

Add curl_easy_setopt(curl, CURLOPT_TIMEOUT, 10L); for a 10-second timeout.
Use CURLOPT_USERAGENT to set a user agent if required.
Enable SSL verification in production with proper CA bundle paths if needed.

Basically just initialize curl, set options, perform the request, and clean up. The callback collects incoming data. With libcurl, it's straightforward once set up.

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