why 0? c++

Question

#include <iostream>
using namespace std;

int main() {
double a = 0.1, b=0.2,c=0.3;
cout<<((a+b)==c);

return 0;
}

Answer 1

You compare doubles for equality.

See floating point precision:
https://learn.microsoft.com/en-us/cpp/build/why-floating-point-numbers-may-lose-precision?view=msvc-170

Answer 2

This is described in the link that I provided.

Answer 3

so how to compare floats?

Answer 4

You can compare floats only up to a predefined precision. That precision is up to you and the requirements of your program.