C++ floating point precision
- by Davinel
double a = 0.3;
std::cout.precision(20);
std::cout << a << std::endl;
result: 0.2999999999999999889
double a, b;
a = 0.3;
b = 0;
for (char i = 1; i <= 50; i++) {
b = b + a;
};
std::cout.precision(20);
std::cout << b << std::endl;
result: 15.000000000000014211
So.. 'a' is smaller than it should be.
But if we take 'a' 50 times - result will be bigger than it should be.
Why is this?
And how to get correct result in this case?
