Csharp/C Sharp/Class Interface/struct
Содержание
- 1 Calling a Function with a Structure Parameter
- 2 C# always creates a structure instance as a value-type variable even using the new operator
- 3 Conversions Between Structs 1
- 4 Conversions Between Structs 2
- 5 Copy a struct
- 6 Define struct and use it
- 7 Defining functions for structs
- 8 Demonstates assignment operator on structures and classes.
- 9 Demonstrate a structure
- 10 demonstrates a custom constructor function for a structure
- 11 demonstrates using a structure to return a group of variables from a function
- 12 Illustrates the use of a struct
- 13 Issue an error message if you do not initialize all of the fields in a structure
- 14 Structs And Enums
- 15 Structs (Value Types):A Point Struct
- 16 Structs (Value Types):Structs and Constructors
- 17 Structures are good when grouping data
Calling a Function with a Structure Parameter
<source lang="csharp"> /* 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);
}
}
}
</source>
C# always creates a structure instance as a value-type variable even using the new operator
<source lang="csharp"> /* C# Programming Tips & Techniques by Charles Wright, Kris Jamsa Publisher: Osborne/McGraw-Hill (December 28, 2001) ISBN: 0072193794
- /
// // ValType.cs -- Demonstrates that C# always creates a structure instance as // a value-type variable even using the new operator. // Compile this program using the following command line: // C:>csc ValType.cs // namespace nsValType {
using System;
public struct POINT
{
public int cx;
public int cy;
}
public class ValType
{
static public void Main()
{
POINT point1;
point1.cx = 42;
point1.cy = 56;
ModifyPoint (point1);
Console.WriteLine ("In Main() point2 = ({0}, {1})", point1.cx, point1.cy);
POINT point2 = new POINT ();
// point2.cx = 42;
// point2.cy = 56;
Console.WriteLine ();
ModifyPoint (point2);
Console.WriteLine ("In Main() point2 = ({0}, {1})", point2.cx, point2.cy);
}
static public void ModifyPoint (POINT pt)
{
pt.cx *= 2;
pt.cy *= 2;
Console.WriteLine ("In ModifyPoint() pt = ({0}, {1})", pt.cx, pt.cy);
}
}
}
</source>
Conversions Between Structs 1
<source lang="csharp"> /* A Programmer"s Introduction to C# (Second Edition) by Eric Gunnerson Publisher: Apress L.P. ISBN: 1-893115-62-3
- /
// 24 - User-Defined Conversions\Conversions Between Structs // copyright 2000 Eric Gunnerson using System; using System.Text; struct RomanNumeral {
public RomanNumeral(short value)
{
if (value > 5000)
throw(new ArgumentOutOfRangeException());
this.value = value;
}
public static explicit operator RomanNumeral(
short value)
{
RomanNumeral retval;
retval = new RomanNumeral(value);
return(retval);
}
public static implicit operator short(
RomanNumeral roman)
{
return(roman.value);
}
static string NumberString(
ref int value, int magnitude, char letter)
{
StringBuilder numberString = new StringBuilder();
while (value >= magnitude)
{
value -= magnitude;
numberString.Append(letter);
}
return(numberString.ToString());
}
public static implicit operator string(
RomanNumeral roman)
{
int temp = roman.value;
StringBuilder retval = new StringBuilder();
retval.Append(RomanNumeral.NumberString(ref temp, 1000, "M"));
retval.Append(RomanNumeral.NumberString(ref temp, 500, "D"));
retval.Append(RomanNumeral.NumberString(ref temp, 100, "C"));
retval.Append(RomanNumeral.NumberString(ref temp, 50, "L"));
retval.Append(RomanNumeral.NumberString(ref temp, 10, "X"));
retval.Append(RomanNumeral.NumberString(ref temp, 5, "V"));
retval.Append(RomanNumeral.NumberString(ref temp, 1, "I"));
return(retval.ToString());
}
public static implicit operator BinaryNumeral(RomanNumeral roman)
{
return(new BinaryNumeral((short) roman));
}
public static explicit operator RomanNumeral(
BinaryNumeral binary)
{
return(new RomanNumeral((short) binary));
}
private short value;
} struct BinaryNumeral {
public BinaryNumeral(int value)
{
this.value = value;
}
public static implicit operator BinaryNumeral(
int value)
{
BinaryNumeral retval = new BinaryNumeral(value);
return(retval);
}
public static implicit operator int(
BinaryNumeral binary)
{
return(binary.value);
}
public static implicit operator string(
BinaryNumeral binary)
{
StringBuilder retval = new StringBuilder();
return(retval.ToString());
}
private int value;
} public class ConversionsConversionsBetweenStructs2 {
public static void Main()
{
RomanNumeral roman = new RomanNumeral(122);
BinaryNumeral binary;
binary = roman;
roman = (RomanNumeral) binary;
}
}
</source>
Conversions Between Structs 2
<source lang="csharp"> /* A Programmer"s Introduction to C# (Second Edition) by Eric Gunnerson Publisher: Apress L.P. ISBN: 1-893115-62-3
- /
// 24 - User-Defined Conversions\Conversions Between Structs // copyright 2000 Eric Gunnerson using System; using System.Text; struct RomanNumeral {
public RomanNumeral(short value)
{
if (value > 5000)
throw(new ArgumentOutOfRangeException());
this.value = value;
}
public static explicit operator RomanNumeral(
short value)
{
RomanNumeral retval;
retval = new RomanNumeral(value);
return(retval);
}
public static implicit operator short(
RomanNumeral roman)
{
return(roman.value);
}
static string NumberString(
ref int value, int magnitude, char letter)
{
StringBuilder numberString = new StringBuilder();
while (value >= magnitude)
{
value -= magnitude;
numberString.Append(letter);
}
return(numberString.ToString());
}
public static implicit operator string(
RomanNumeral roman)
{
int temp = roman.value;
StringBuilder retval = new StringBuilder();
retval.Append(RomanNumeral.NumberString(ref temp, 1000, "M"));
retval.Append(RomanNumeral.NumberString(ref temp, 500, "D"));
retval.Append(RomanNumeral.NumberString(ref temp, 100, "C"));
retval.Append(RomanNumeral.NumberString(ref temp, 50, "L"));
retval.Append(RomanNumeral.NumberString(ref temp, 10, "X"));
retval.Append(RomanNumeral.NumberString(ref temp, 5, "V"));
retval.Append(RomanNumeral.NumberString(ref temp, 1, "I"));
return(retval.ToString());
}
private short value;
} struct BinaryNumeral {
public BinaryNumeral(int value)
{
this.value = value;
}
public static implicit operator BinaryNumeral(
int value)
{
BinaryNumeral retval = new BinaryNumeral(value);
return(retval);
}
public static implicit operator int(
BinaryNumeral binary)
{
return(binary.value);
}
public static implicit operator string(
BinaryNumeral binary)
{
StringBuilder retval = new StringBuilder();
return(retval.ToString());
}
private int value;
} public class ConversionsBetweenStructs1 {
public static void Main()
{
RomanNumeral roman = new RomanNumeral(12);
BinaryNumeral binary;
binary = (BinaryNumeral)(int)roman;
}
}
</source>
Copy a struct
<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852
- /
// Copy a struct.
using System;
// Define a structure. struct MyStruct {
public int x;
}
// Demonstrate structure assignment. public class StructAssignment {
public static void Main() {
MyStruct a;
MyStruct b;
a.x = 10;
b.x = 20;
Console.WriteLine("a.x {0}, b.x {1}", a.x, b.x);
a = b;
b.x = 30;
Console.WriteLine("a.x {0}, b.x {1}", a.x, b.x);
}
}
</source>
Define struct and use it
<source lang="csharp"> /*
* C# Programmers Pocket Consultant * Author: Gregory S. MacBeth * Email: gmacbeth@comporium.net * Create Date: June 27, 2003 * Last Modified Date: */
using System; namespace Client.Chapter_3___Structs__Enums__Arrays_and_Classes {
public struct MyStruct
{
public int MyInt;
public long MyLong;
public string MyString;
}
public class StructsChapter_3___Structs__Enums__Arrays_and_Classes
{
static void Main(string[] args)
{
MyStruct TheStruct;
TheStruct.MyInt = 0;
TheStruct.MyLong = 0;
TheStruct.MyString = "Hello World";
}
}
}
</source>
Defining functions for structs
<source lang="csharp"> using System; struct Dimensions {
public double Length;
public double Width;
Dimensions(double length, double width) { Length = length; Width = width; }
public double Diagonal {
get {
return Math.Sqrt(Length * Length + Width * Width);
}
}
}
</source>
Demonstates assignment operator on structures and classes.
<source lang="csharp"> /* C# Programming Tips & Techniques by Charles Wright, Kris Jamsa Publisher: Osborne/McGraw-Hill (December 28, 2001) ISBN: 0072193794
- /
// // CmpStCls.cs -- Demonstates assignment operator on structures and classes. // Compile this program with the following command line: // C:>csc CmpStCls.cs // namespace nsCompare {
using System;
// // Define a structure containing the x and y coordinates of a point
struct stPoint
{
public int cx;
public int cy;
}
// // Define a class containing the x and y coordinates of a point
class clsPoint
{
public int cx;
public int cy;
}
public class CmpStCls
{
static public void Main ()
{
// Declare two structure variables
stPoint spt1, spt2;
// Initialize the members of only one structure
spt1.cx = 42;
spt1.cy = 24;
// Assign the first structure to the first
spt2 = spt1;
// Now modify the first structure
spt1.cx = 12;
spt1.cy = 18;
// Show the results
Console.WriteLine ("For structures:");
Console.WriteLine ("\tThe point for spt1 is ({0}, {1})", spt1.cx, spt1.cy);
Console.WriteLine ("\tThe point for spt2 is ({0}, {1})", spt2.cx, spt2.cy);
// Now do the same thing with instances of the class
clsPoint cpt1, cpt2;
cpt1 = new clsPoint();
// Initialize the members of only one class instance
cpt1.cx = 42;
cpt1.cy = 24;
// Assign the first class instance to the second
cpt2 = cpt1;
// Modify the first class
cpt1.cx = 12;
cpt2.cy = 18;
// Show the results
Console.WriteLine ("\r\nFor structures:");
Console.WriteLine ("\tThe point for cpt1 is ({0}, {1})", cpt1.cx, cpt1.cy);
Console.WriteLine ("\tThe point for cpt2 is ({0}, {1})", cpt2.cx, cpt2.cy);
}
}
}
</source>
Demonstrate a structure
<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852
- /
// Demonstrate a structure.
using System;
// Define a structure. struct Book {
public string author;
public string title;
public int copyright;
public Book(string a, string t, int c) {
author = a;
title = t;
copyright = c;
}
}
// Demonstrate Book structure. public class StructDemo1 {
public static void Main() {
Book book1 = new Book("Herb Schildt",
"C# A Beginner"s Guide",
2001); // explicit constructor
Book book2 = new Book(); // default constructor
Book book3; // no constructor
Console.WriteLine(book1.title + " by " + book1.author +
", (c) " + book1.copyright);
Console.WriteLine();
if(book2.title == null)
Console.WriteLine("book2.title is null.");
// now, give book2 some info
book2.title = "Brave New World";
book2.author = "Aldous Huxley";
book2.copyright = 1932;
Console.Write("book2 now contains: ");
Console.WriteLine(book2.title + " by " + book2.author +
", (c) " + book2.copyright);
Console.WriteLine();
// Console.WriteLine(book3.title); // error, must initialize first
book3.title = "Red Storm Rising"; Console.WriteLine(book3.title); // now OK }
}
</source>
demonstrates a custom constructor function for a structure
<source lang="csharp"> /* C# Programming Tips & Techniques by Charles Wright, Kris Jamsa Publisher: Osborne/McGraw-Hill (December 28, 2001) ISBN: 0072193794
- /
// tm2.cs - demonstrates a custom constructor function for a structure // Compile this program using the following command line: // D:>csc tm2.cs // namespace nsStructure {
using System;
using System.Globalization;
struct tm
{
public tm (DateTime tmVal)
{
tm_sec = tmVal.Second;
tm_min = tmVal.Minute;
tm_hour = tmVal.Hour;
tm_mday = tmVal.Day;
tm_mon = tmVal.Month - 1;
tm_year = tmVal.Year - 1900;
tm_wday = (int) tmVal.DayOfWeek;
tm_yday = tmVal.DayOfYear;
TimeZone tz = TimeZone.CurrentTimeZone;
tm_isdst = tz.IsDaylightSavingTime (tmVal) == true ? 1 : 0;
}
public int tm_sec; // Seconds after the minute
public int tm_min; // Minutes after the hour
public int tm_hour; // Hours since midnight
public int tm_mday; // The day of the month
public int tm_mon; // The month (January = 0)
public int tm_year; // The year (00 = 1900)
public int tm_wday; // The day of the week (Sunday = 0)
public int tm_yday; // The day of the year (Jan. 1 = 1)
public int tm_isdst; // Flag to indicate if DST is in effect
public override string ToString()
{
const string wDays = "SunMonTueWedThuFriSat";
const string months = "JanFebMarAprMayJunJulAugSepOctNovDec";
return (String.Format ("{0} {1} {2,2:00} " +
"{3,2:00}:{4,2:00}:{5,2:00} {6}\n",
wDays.Substring (3 * tm_wday, 3),
months.Substring (3 * tm_mon, 3),
tm_mday, tm_hour, tm_min,
tm_sec, tm_year + 1900));
}
}
public class tm2Demo
{
static public void Main()
{
DateTime timeVal = DateTime.Now;
tm tmNow = new tm (timeVal);
Console.WriteLine (tmNow);
}
}
}
</source>
demonstrates using a structure to return a group of variables from a function
<source lang="csharp"> /* C# Programming Tips & Techniques by Charles Wright, Kris Jamsa Publisher: Osborne/McGraw-Hill (December 28, 2001) ISBN: 0072193794
- /
// tm.cs - demonstrates using a structure to return a group of variables // from a function // // Compile this program using the following command line: // D:>csc tm.cs // namespace nsStructure {
using System;
using System.Globalization;
public struct tm
{
public int tm_sec; // Seconds after the minute
public int tm_min; // Minutes after the hour
public int tm_hour; // Hours since midnight
public int tm_mday; // The day of the month
public int tm_mon; // The month (January = 0)
public int tm_year; // The year (00 = 1900)
public int tm_wday; // The day of the week (Sunday = 0)
public int tm_yday; // The day of the year (Jan. 1 = 1)
public int tm_isdst; // Flag to indicate if DST is in effect
}
public class tmDemo
{
static public void Main()
{
DateTime timeVal = DateTime.Now;
tm tmNow = LocalTime (timeVal);
string strTime = AscTime (tmNow);
Console.WriteLine (strTime);
}
static public tm LocalTime(DateTime tmVal)
{
tm time;
time.tm_sec = tmVal.Second;
time.tm_min = tmVal.Minute;
time.tm_hour = tmVal.Hour;
time.tm_mday = tmVal.Day;
time.tm_mon = tmVal.Month - 1;
time.tm_year = tmVal.Year - 1900;
time.tm_wday = (int) tmVal.DayOfWeek;
time.tm_yday = tmVal.DayOfYear;
TimeZone tz = TimeZone.CurrentTimeZone;
time.tm_isdst = tz.IsDaylightSavingTime (tmVal) == true ? 1 : 0;
return (time);
}
// // Returns a string representing a time using UNIX format
static public string AscTime (tm time)
{
const string wDays = "SunMonTueWedThuFriSat";
const string months = "JanFebMarAprMayJunJulAugSepOctNovDec";
string strTime = String.Format ("{0} {1} {2,2:00} " +
"{3,2:00}:{4,2:00}:{5,2:00} {6}\n",
wDays.Substring (3 * time.tm_wday, 3),
months.Substring (3 * time.tm_mon, 3),
time.tm_mday, time.tm_hour,
time.tm_min, time.tm_sec, time.tm_year + 1900);
return (strTime);
}
}
}
</source>
Illustrates the use of a struct
<source lang="csharp"> /* Mastering Visual C# .NET by Jason Price, Mike Gunderloy Publisher: Sybex; ISBN: 0782129110
- /
/*
Example5_15.cs illustrates the use of a struct
- /
// declare the Rectangle struct struct Rectangle {
// declare the fields
public int Width;
public int Height;
// define a constructor
public Rectangle(int Width, int Height)
{
this.Width = Width;
this.Height = Height;
}
// define the Area() method
public int Area()
{
return Width * Height;
}
}
public class Example5_15 {
public static void Main()
{
// create an instance of a Rectangle
System.Console.WriteLine("Creating a Rectangle instance");
Rectangle myRectangle = new Rectangle(2, 3);
// display the values for the Rectangle instance
System.Console.WriteLine("myRectangle.Width = " + myRectangle.Width);
System.Console.WriteLine("myRectangle.Height = " + myRectangle.Height);
// call the Area() method of the Rectangle instance
System.Console.WriteLine("myRectangle.Area() = " + myRectangle.Area());
}
}
</source>
Issue an error message if you do not initialize all of the fields in a structure
<source lang="csharp"> /* C# Programming Tips & Techniques by Charles Wright, Kris Jamsa Publisher: Osborne/McGraw-Hill (December 28, 2001) ISBN: 0072193794
- /
// // Struct.cs - Issue an error message if you do not initialize all of // the fields in a structure // // Compile this program with the following command line: // C:>csc Struct.cs // using System; namespace nsStruct {
struct POINT
{
public int cx;
public int cy;
public int var;
public override string ToString ()
{
return ("(" + cx + ", " + cy + ")");
}
}
public class StructDemo2
{
static public void Main ()
{
POINT pt;
pt.cx = 24;
pt.cy = 42;
Console.WriteLine (pt);
// Console.WriteLine ("(" + pt.cx + ", " + pt.cy + ")");
} }
}
</source>
Structs And Enums
<source lang="csharp"> using System; using System.Collections.Generic; using System.Text; struct Date {
public Date(int ccyy, Month mm, int dd) {
this.year = ccyy - 1900;
this.month = mm;
this.day = dd - 1;
}
public override string ToString() {
return this.month + " " + (this.day + 1) + " " + (this.year + 1900);
}
private int year;
private Month month;
private int day;
}
enum Month {
January, February, March, April, May, June, July, August, September, October, November, December
} class Program {
static void Entrance() {
Month first = Month.December;
Console.WriteLine(first);
first++;
Console.WriteLine(first);
Date defaultDate = new Date();
Console.WriteLine(defaultDate);
Date halloween = new Date(2008, Month.October, 31);
Console.WriteLine(halloween);
}
static void Main() {
try {
Entrance();
} catch (Exception ex) {
Console.WriteLine(ex.Message);
}
}
}
</source>
Structs (Value Types):A Point Struct
<source lang="csharp"> using System; struct Point {
public Point(int x, int y)
{
this.x = x;
this.y = y;
}
public override string ToString()
{
return(String.Format("({0}, {1})", x, y));
}
public int x;
public int y;
} public class APointStruct {
public static void Main()
{
Point start = new Point(5, 5);
Console.WriteLine("Start: {0}", start);
}
}
</source>
Structs (Value Types):Structs and Constructors
<source lang="csharp"> using System; struct Point {
int x;
int y;
Point(int x, int y)
{
this.x = x;
this.y = y;
}
public override string ToString()
{
return(String.Format("({0}, {1})", x, y));
}
} public class StructsandConstructors {
public static void Main()
{
Point[] points = new Point[5];
Console.WriteLine("[2] = {0}", points[2]);
}
}
</source>
Structures are good when grouping data
<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852
- /
// Structures are good when grouping data.
using System;
// Define a packet structure. struct PacketHeader {
public uint packNum; // packet number public ushort packLen; // length of packet
}
// Use PacketHeader to create an e-commerce transaction record. class Transaction {
static uint transacNum = 0;
PacketHeader ph; // incorporate PacketHeader into Transaction
string accountNum;
double amount;
public Transaction(string acc, double val) {
// create packet header
ph.packNum = transacNum++;
ph.packLen = 512; // arbitrary length
accountNum = acc;
amount = val;
}
// Simulate a transaction.
public void sendTransaction() {
Console.WriteLine("Packet #: " + ph.packNum +
", Length: " + ph.packLen +
",\n Account #: " + accountNum +
", Amount: {0:C}\n", amount);
}
}
// Demonstrate Packet public class PacketDemo {
public static void Main() {
Transaction t = new Transaction("31243", -100.12);
Transaction t2 = new Transaction("AB4655", 345.25);
Transaction t3 = new Transaction("8475-09", 9800.00);
t.sendTransaction();
t2.sendTransaction();
t3.sendTransaction();
}
}
</source>
