Find out if a rectangle is inside another rectangle [C]

Question

So I have two rectangles, the user has to input the bottom left point (x1,y1, but y1 is always 0) and the top right point (x2,y2), and I have to find out if one of them is completely inside the other (or they are exactly the same).

And it'll be a bit harder since I'll actually have to make the program so the user can decide how many rectangles they want to create, but at first I'd be happy to know how to check in the case of 2 rectangles.

Answer 1

Below is comparing the sides of the inner rectangle to the sides of the outer rectangle

if Right2 < Right1 && Left2 > Left1 && Top2 > Top1 && Bottom2 < Bottom1

Implementation:

struct RECT
{
    double x,y, w,h;

    RECT(double a,double b,double c,double d)
    {
    x=a; y=b; w=c; h=d;
    }
};


bool contains(RECT R1, RECT R2)
{
    if (   (R2.x+R2.w) < (R1.x+R1.w)
        && (R2.x) > (R1.x)
        && (R2.y) > (R1.y)
        && (R2.y+R2.h) < (R1.y+R1.h)
        )
    {
        return true;
    }
    else
    {
        return false;
    }
}

Answer 2

Well, by definition one rectangle is inside of another if all the points of the inner rectangle are within the outer rectangle. Using a bit of geometry you can boil it down to checking whether the two opposite corners of the inner rectangle are in the outer rectangle.