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  1. #include <boost/optional.hpp>
  2. #include <boost/logic/tribool.hpp>
  3. #include <iostream>
  4.  
  5. void foo(boost::optional<bool> opb){
  6.  
  7.   if(!opb)
  8.     std::cout << "none" << std::endl;
  9.   else if(*opb)
  10.     std::cout << "true" << std::endl;
  11.   else
  12.     std::cout << "false" << std::endl;
  13.  
  14. }
  15.  
  16. void bar(boost::logic::tribool trb){
  17.  
  18.   if(trb)
  19.     std::cout << "true"  << std::endl;
  20.   else if(!trb)
  21.     std::cout << "false" << std::endl;
  22.   else
  23.     std::cout << "indeterminate" << std::endl;
  24.  
  25. }
  26.  
  27. int main(){
  28.   // optional<bool> a: 未初期化, b: true, c: false
  29.   boost::optional<bool> a, b = true, c = false, d = boost::none;
  30.  
  31.   // tribool v: 未初期化, x: true, y: false, z: indeterminate
  32.   boost::logic::tribool v, x = true, y = false, z = boost::logic::indeterminate;
  33.  
  34.   std::cout << "a: ";
  35.   foo(a);
  36.  
  37.   std::cout << "b: ";
  38.   foo(b);
  39.  
  40.   std::cout << "c: ";
  41.   foo(c);
  42.  
  43.   std::cout << "d: ";
  44.   foo(d);
  45.  
  46.   std::cout << std::endl;
  47.  
  48.   std::cout << "v: ";
  49.   bar(v);
  50.  
  51.   std::cout << "x: ";
  52.   bar(x);
  53.  
  54.   std::cout << "y: ";
  55.   bar(y);
  56.  
  57.   std::cout << "z: ";
  58.   bar(z);
  59.  
  60.   return 0;
  61. }
Success #stdin #stdout 0s 2728KB
comments (?)
stdin
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Standard input is empty
stdout
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a: none
b: true
c: false
d: none

v: false
x: true
y: false
z: indeterminate
https://ideone.com/aaKgO
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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