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  1. #include <iostream>
  2. #include <limits>
  3.  
  4. template<typename Desired, typename Given>
  5. constexpr Desired narrow_cast(Given arg) {
  6. 	static_assert(std::is_integral<Desired>::value, "Only integer types are supported");
  7. 	static_assert(std::is_integral<Given>::value, "Only integer types are supported");
  8.  
  9. 	auto min = std::numeric_limits<Desired>::min();
  10. 	auto max = std::numeric_limits<Desired>::max();
  11.  
  12. 	auto different_signs = std::is_signed<Given>::value xor std::is_signed<Desired>::value;
  13. 	if(sizeof(Desired) == sizeof(Given) && different_signs && arg < 0) {
  14. 		return 0;
  15. 	}
  16.  
  17. 	return 
  18. 		min > arg? min:
  19. 		max < arg? max: 
  20. 		arg;
  21. }
  22.  
  23. int main() {
  24. 	std::cout << narrow_cast<short>(100000) << std::endl;
  25. 	std::cout << narrow_cast<unsigned short>(100000) << std::endl;
  26. 	std::cout << narrow_cast<unsigned short>(-100000) << std::endl;
  27. 	std::cout << narrow_cast<int>(-1) << std::endl;
  28. 	std::cout << narrow_cast<unsigned int>(-1) << std::endl;
  29. 	std::cout << narrow_cast<unsigned short>(-1) << std::endl;
  30. 	return 0;
  31. }
Success #stdin #stdout 0s 15240KB
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https://ideone.com/HF4Yr1
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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