-0.1+0.1=-1.38778e-016

#include <windows.h>
#include <iostream>
#include <iomanip>
#include <fstream>
#include <cmath>
#include <cstdlib>
using namespace std;
 
 
int main()
{
    SetConsoleOutputCP(1251);
 
    double a=-1,b=1,d=0.1;
 
    double x=a;
    double y;
 
    while (x<=b)
    {
        
           
            cout<<x<<" "<<x+d<<endl;
        x+=d;
    }
 
   
        system  ("PAUSE");
}

int main()
{
double x=-0.1;
x+=0.1;
cout<<x;
}

 std::cout << std::fixed << x << " " << x+d << std::endl;

#include <iostream>
int main ()
{
 double x;
 double r;
 char c;
 x=2.67;
 r=x;
 r-=x;
 std::cout<<r<<std::endl;
 return 0;
}

#include <iostream>
 
int main ()
{
 double x;
 double r;
 x=2.67;
 r=x;
 while (r!=0)
 {
  r/=x;
 }
 std::cout<<r<<std::endl;
 return 0;
}