Why can't we compare temp and double datatypes? [duplicate]

This question already has an answer here:

• Is floating point math broken? 22 answers

Let's take this code

#include<iostream>
#include<conio.h>

int main()
{
    float x = 3.1;
    double y = 3.1;
    if(x==y)
    {
        cout<<"Yes";
        getch();
    }
    else
    {
        cout<<"No";
        getch();
    }
return 0;
}

So apparently, this code should print "Yes" on the screen but it does not. It just skip the x==y condition even x and y are equal and execute the else statement. Why can't we compare float and double. Do I need to use type casting or something else like that?