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  1. #include <iostream>
  2. using namespace std;
  3.  
  4.  
  5. struct A
  6. {
  7. 	bool bValid;
  8. 	int  value;
  9. 	bool isValid() { return bValid; }
  10.  
  11. 	A(bool b = false) : bValid(b) {}
  12. 	A(int v) : bValid(true), value(v)  {} 
  13.  
  14. 	operator bool() const
  15. 	{
  16. 		return bValid;
  17. 	}
  18.  
  19. };
  20.  
  21. A foo()
  22. {
  23.     return 5;	
  24. }
  25.  
  26. A bar()
  27. {
  28. 	return false;
  29. }
  30.  
  31. int main() {
  32.  
  33. 	if (auto a = foo())
  34. 	{
  35. 		cout<<"a = "<<a.value<<"\n";
  36. 	}
  37. 	else
  38. 	{
  39. 		cout<<"a is not valid\n";
  40. 	}
  41.  
  42. 	if (auto b = bar())
  43. 	{
  44. 		cout<<"b = "<<b.value<<"\n";
  45. 	}
  46. 	else
  47. 	{
  48. 		cout<<"b is not valid\n";
  49. 	}
  50.  
  51. 	return 0;
  52. }
Success #stdin #stdout 0s 4332KB
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stdin
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Standard input is empty
stdout
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a = 5
b is not valid
https://ideone.com/GgfjNa
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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