Calling a Function with a Structure Parameter

/*
A Programmer's Introduction to C# (Second Edition)
by Eric Gunnerson

Publisher: Apress  L.P.
ISBN: 1-893115-62-3
*/

// 31 - Interop\Calling Native DLL Functions\Calling a Function with a Structure Parameter
// copyright 2000 Eric Gunnerson
using System;
using System.Runtime.InteropServices;

struct Point
{
    public int x;
    public int y;
    
    public override string ToString()
    {
        return(String.Format("({0}, {1})", x, y));
    }
}

struct Rect
{
    public int left;
    public int top;
    public int right;
    public int bottom;
    
    public override string ToString()
    {
        return(String.Format("({0}, {1})\n    ({2}, {3})", left, top, right, bottom));
    }
}

struct WindowPlacement
{
    public uint length;
    public uint flags;
    public uint showCmd;
    public Point minPosition;
    public Point maxPosition;
    public Rect normalPosition;    
    
    public override string ToString()
    {
        return(String.Format("min, max, normal:\n{0}\n{1}\n{2}",
        minPosition, maxPosition, normalPosition));
    }
}

public class CallingaFunctionwithaStructureParameterWindow
{
    [DllImport("user32")]
    static extern int GetForegroundWindow();
    
    [DllImport("user32")]
    static extern bool GetWindowPlacement(int handle, ref WindowPlacement wp);
    
    public static void Main()
    {
        int window = GetForegroundWindow();
        
        WindowPlacement wp = new WindowPlacement();
        wp.length = (uint) Marshal.SizeOf(wp);
        
        bool result = GetWindowPlacement(window, ref wp);
        
        if (result)
        {
            Console.WriteLine(wp);
        }
    } 
}

1.	Structs And Enums
2.	Define struct and use it
3.	Demonstrate a structure
4.	Copy a struct
5.	Structures are good when grouping data
6.	demonstrates a custom constructor function for a structure
7.	Defining functions for structs
8.	demonstrates using a structure to return a group of variables from a function
9.	Demonstates assignment operator on structures and classes.
10.	Issue an error message if you do not initialize all of the fields in a structure
11.	Illustrates the use of a struct
12.	C# always creates a structure instance as a value-type variable even using the new operator
13.	Structs (Value Types):A Point Struct
14.	Structs (Value Types):Structs and Constructors
15.	Conversions Between Structs 1
16.	Conversions Between Structs 2

Calling a Function with a Structure Parameter : struct « Class Interface « C# / C Sharp

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