How do I interoperate with C APIs std::expected (when available) in C++?

Interoperating with C APIs using std::expected in C++ allows for better error handling compared to traditional mechanisms such as return codes or error globals. std::expected provides a way to encapsulate a result that can either be a successful value or an error. This is particularly useful when dealing with C APIs that typically return error codes.

Using std::expected with C APIs

To interoperate with C APIs, you can wrap the C function calls with std::expected to handle success and error states in a more manageable way. Below is an example of how this can be done:

#include #include // C API Function Declaration extern "C" { int c_api_function(int input, const char** error); } // C++ Wrapper Function std::expected cpp_wrapper_function(int input) { const char* error_message = nullptr; int result = c_api_function(input, &error_message); if (result < 0) { return std::unexpected(std::string(error_message)); } return result; } int main() { auto result = cpp_wrapper_function(5); if (result) { std::cout << "Success: " << *result << std::endl; } else { std::cout << "Error: " << result.error() << std::endl; } return 0; }

C++ interop std::expected C API error handling modern C++ C++ wrapper

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