As a senior engineer with a background in algo trading in C++ and R programming in statistics, you may find yourself frequently using REST APIs to retrieve data and perform various actions. When making requests to a REST API, it's essential to handle the responses appropriately.

In C++, you can use libraries like cpprest to make HTTP requests and handle API responses. Let's take a look at an example:

1#include <iostream>
2#include <cpprest/http_client.h>
3
4using namespace std;
5using namespace web::http;
6using namespace web::http::client;
7
8int main() {
9  // Create an HTTP client
10  http_client client(U("https://api.example.com"));
11
12  // Make a GET request
13  client.request(methods::GET, U("/api/resource")).then([](http_response response) {
14    // Process the response
15    if (response.status_code() == status_codes::OK) {
16      // Successful response
17      cout << "GET request successful!" << endl;
18    } else {
19      // Failed response
20      cout << "GET request failed!" << endl;
21    }
22  }).wait();
23
24  return 0;
25}

In this code snippet, we create an HTTP client using the http_client class from the cpprest library. We then make a GET request to the /api/resource endpoint of the API. The response is handled in the callback function specified in the then method. We check the status code of the response to determine if the request was successful or not. If the response status code is status_codes::OK, we output "GET request successful!"; otherwise, we output "GET request failed!".

Handling API responses involves more than just checking the status code. Depending on the API, you may need to parse the response body, extract relevant data, handle errors, and perform additional actions based on the response.

When parsing response bodies, you can use JSON libraries like nlohmann/json or RapidJSON to extract data from JSON responses. If the response is in XML format, you can use XML parsing libraries like pugixml.

Additionally, it's important to handle errors gracefully. If the API returns an error response, you should provide meaningful error messages to the user and handle any exceptions that occur during the request.

Handling API responses effectively ensures that your application can handle different scenarios and provide a smooth experience for users. It allows you to extract relevant information, take appropriate actions based on responses, and handle errors in a user-friendly manner.

xxxxxxxxxx

#include <iostream>

#include <cpprest/http_client.h>

​

using namespace std;

using namespace web::http;

using namespace web::http::client;

​

int main() {

  // Create an HTTP client

  http_client client(U("https://api.example.com"));

​

  // Make a GET request

  client.request(methods::GET, U("/api/resource")).then([](http_response response) {

    // Process the response

    if (response.status_code() == status_codes::OK) {

      // Successful response

      cout << "GET request successful!" << endl;

    } else {

      // Failed response

      cout << "GET request failed!" << endl;

    }

  }).wait();

​

  return 0;

}