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  1. #include <iostream>
  2. #include <iomanip>
  3. #include <cmath>
  4. using namespace std;
  5.  
  6. int main() {
  7. 	double d_total = 1.2345678;
  8. 	float f_total = (float)d_total;
  9. 	double some_dbl = 6.7809123;
  10.  
  11. 	double actual = (d_total * some_dbl);
  12. 	float no_cast = (float)(f_total * some_dbl);
  13. 	float with_cast = (float)(f_total * (float)some_dbl);
  14.  
  15. 	cout << "actual:               " << setprecision(25) << actual << endl;
  16. 	cout << "no_cast:              " << setprecision(25) << no_cast << endl;
  17. 	cout << "with_cast:            " << setprecision(25) << with_cast << endl;
  18. 	cout << "no_cast, nextafter:   " << setprecision(25) << nextafter(no_cast, 500.0f) << endl;
  19.  
  20. 	cout << endl;
  21.  
  22. 	cout << "Diff no_cast:   " << setprecision(25) << actual - no_cast << endl;
  23. 	cout << "Diff with_cast: " << setprecision(25) << with_cast - actual << endl;
  24. 	return 0;
  25. }
Success #stdin #stdout 0s 3340KB
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stdin
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Standard input is empty
stdout
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actual:               8.371495980203938813701825
no_cast:              8.37149524688720703125
with_cast:            8.3714962005615234375
no_cast, nextafter:   8.3714962005615234375

Diff no_cast:   7.333167317824518249835819e-07
Diff with_cast: 2.203575846237981750164181e-07
https://ideone.com/sRXj1z
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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