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for C++ programmers

libcurl provides a C API. C and C++ are similar but not the same. There are a few things to keep in mind when using libcurl in C++.
Strings are C strings, not C++ string objects
When you pass strings to libcurl's APIs that accept char * that means you cannot pass in C++ strings or objects to those functions.
For example, if you build a string with C++ and then want that string used as a URL:
std::string url = "https://example.com/foo.asp?name=" + i;
curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
Callback considerations
Since libcurl is a C library, it does not know anything about C++ member functions or objects. You can overcome this "limitation" with relative ease using for a static member function that is passed a pointer to the class.
Here's an example of a write callback using a C++ method as callback:
// f is the pointer to your object.
static size_t YourClass::func(void *buffer, size_t sz, size_t n, void *f)
{
  // Call non-static member function.
  static_cast<YourClass*>(f)->nonStaticFunction();
}
​
// This is how you pass pointer to the static function:
curl_easy_setopt(hcurl, CURLOPT_WRITEFUNCTION, YourClass::func);
curl_easy_setopt(hcurl, CURLOPT_WRITEDATA, this);

Non-blocking HTTP form-post

HTTP with libcurl

Last modified 7mo ago

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Strings are C strings, not C++ string objects

Callback considerations