boost variant

Boost Variant resembles union. You can store values of different types in a boost::variant.

#include <boost/variant.hpp>

#include <string>

int main() {

  boost::variant<double, char, std::string> v;

  v = 3.14;

  v = 'A';

  v = "Boost";

}

boost::variant is a template, at least one parameter must be specified. One or more template parameters specify the supported types.

2. accessing values in boost::variant with boost::get()

#include <boost/variant.hpp>

#include <string>

#include <iostream>

int main() {

  boost::variant<double, char, std::string> v;

  v = 3.14;

  std::cout << boost::get<double>(v) << std::endl;

  v = 'A';

  std::cout << boost::get<char>(v) << std::endl;

  v = "Boost";

  std::cout << boost::get<std::string>(v) << std::endl;

  return ;

}

to display the stored values of v, use the free-standing function boost::get().

巴特西

boost variant

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