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  1. #include <iostream>
  2. #include <iomanip>
  3. #include <sstream>
  4. #include <string>
  5. #include <cassert>
  6.  
  7. std::string format(double x, int precision = 2)
  8. {
  9. 	std::ostringstream output;
  10. 	output << std::fixed << std::setprecision(precision) << x;
  11. 	std::string s = output.str();
  12.  
  13. 	if (precision > 0)
  14. 	{
  15. 		const auto pos = s.find_last_not_of('0');
  16. 		assert(pos != std::string::npos);		
  17.  
  18. 		if (pos != s.size() - 1)
  19. 		{
  20. 			const auto count = s[pos] != '.' ? pos + 1 : pos;
  21. 			return s.substr(0, count);
  22. 		}
  23. 	}
  24. 	return s;
  25. }
  26.  
  27. int main()
  28. {
  29. 	std::cout << format(0) << std::endl;
  30. 	std::cout << format(1e-20) << std::endl;
  31. 	std::cout << format(1e+20) << std::endl;
  32. 	std::cout << format(123456.0049999) << std::endl;
  33. 	std::cout << format(123456.005) << std::endl;
  34. 	std::cout << format(123456.695) << std::endl;
  35. 	std::cout << format(0x1.6bcc41e8ffffap+46) << std::endl;
  36. }
Success #stdin #stdout 0s 4528KB
comments (?)
stdin
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Standard input is empty
stdout
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0
0
100000000000000000000
123456
123456.01
123456.7
99999999999999.91
https://ideone.com/2iDTT4
language:
C++ (gcc 8.3)
created:
4 years ago
visibility:
public

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