What is the application of Union in realtime ?

[amaresh_83]

Hi ,

Can anybody will guide me , as what is the application of Union in real time ? .


Thanks,
-Amar

[Rubberman]

Could you please be more explicit as to what you are asking? Are you talking about union structures in a language like C, or something else? And what do you mean by real time? Are you talking about real time as in wall-clock time, or real time as in deterministic scheduling systems?

[amaresh_83]

Yup,

I am talking about union structures in a language like C.

Now come to realtime, :- Real time in usual practical life. in which type project and where we can use it and HOW ?

Thanks
-Amar

[Cabhan]

Gotcha. You are curious what people use unions for in real life.

To start, I have yet to see an actual example of a union being used, so this is really theoretical. They're not particularly useful for most applications.

One thing that you _can_ do with a union is crude subclassing in C. Imagine a setup like this:

struct square
{
    int side;
};

struct circle
{
    int radius;
};

struct rectangle
{
    int side1;
    int side2;
};

union shape_union
{
    struct rectangle *rect;
    struct square *squa;
    struct circle *circ;
};

enum shape_type = { RECTANGLE, SQUARE, CIRCLE };

struct shape_struct
{
    union shape_union shape_u;
    shape_type st;
};

typedef struct shape_struct shape;

We can now write a single function that takes in a shape and computes its area:

int area(shape *s)
{
    if(s == NULL)
        return -1;

    switch(s->st)
    {
        RECTANGLE:
            return st->rect->side1 * st->rect->side2;
        SQUARE:
            return st->squa->side * st->squa->side;
        CIRCLE:
            return st->circ->radius * 2 * PI;
        default:
            /* error */
            return -1;
    }
}

This works by using a union to store any type of shape, and wrapping it in a struct that keeps track of exactly what kind of shape we have.


Does this make sense?

[amaresh_83]

Thanks yar .. goos explaination...

i will try with new stuffs and i ll post ...