从R控制台获取用户输入:Rcpp和std::cin

我一直在做一些练习来学习c ++,并决定将它们集成到R中,因为最终我想为R函数编写c ++后端.我无法找到从R控制台检索用户输入的解决方案.虽然有Rcpp :: Rcout用于打印和返回输出,但似乎没有类似的功能std :: cin ....

#include 
// [[Rcpp::export]]
Rcpp::String cola() {
  Rcpp::Rcout <<"Pick a drink:" <> drink;
  std::string out;
  switch(drink) {
  case 1: out = "Here is your Espresso";
  case 2: out = "Here is your Americano";
  case 3: out = "Here is your Latte";
  case 4: out = "Here is your Cafe dopio";
  case 5: out = "Here is your Tea";
  case 0: out = "Error. Choice was not valid, here is your money back.";
    break;
  default:
    if(drink > 5) {out = "Error. Choice was not valid, here is your money back.";}
  }
  return out;
}

Konrad Rudol.. 5

即使没有Rcpp,std::cin也不适合交互式输入.

要将R控制台与Rcpp一起使用,您需要使用R函数(特别是readline)而不是C++功能.幸运的是,您可以将R对象拉入C++代码:

Environment base = Environment("package:base");
Function readline = base["readline"];
Function as_numeric = base["as.numeric"];

int drink = as(as_numeric(readline("> ")));

Environment base = Environment("package:base");
Function readline = base["readline"];
Function as_numeric = base["as.numeric"];

int drink = as(as_numeric(readline("> ")));