Csharp/C Sharp/Class Interface/Class Variables
Содержание
A Simple Class and Objects
public class Product {
public string make;
public string model;
public string color;
public int yearBuilt;
public void Start() {
System.Console.WriteLine(model + " started");
}
public void Stop() {
System.Console.WriteLine(model + " stopped");
}
}
class MainClass{
public static void Main() {
Product myProduct;
myProduct = new Product();
myProduct.make = "Toyota";
myProduct.model = "MR2";
myProduct.color = "black";
myProduct.yearBuilt = 1995;
System.Console.WriteLine("myProduct details:");
System.Console.WriteLine("myProduct.make = " + myProduct.make);
System.Console.WriteLine("myProduct.model = " + myProduct.model);
System.Console.WriteLine("myProduct.color = " + myProduct.color);
System.Console.WriteLine("myProduct.yearBuilt = " + myProduct.yearBuilt);
myProduct.Start();
myProduct.Stop();
Product redPorsche = new Product();
redPorsche.make = "Porsche";
redPorsche.model = "Boxster";
redPorsche.color = "red";
redPorsche.yearBuilt = 2000;
System.Console.WriteLine( "redPorsche is a " + redPorsche.model);
System.Console.WriteLine("Assigning redPorsche to myProduct");
myProduct = redPorsche;
System.Console.WriteLine("myProduct details:");
System.Console.WriteLine("myProduct.make = " + myProduct.make);
System.Console.WriteLine("myProduct.model = " + myProduct.model);
System.Console.WriteLine("myProduct.color = " + myProduct.color);
System.Console.WriteLine("myProduct.yearBuilt = " + myProduct.yearBuilt);
}
}
Class variables with default value
/*
Learning C#
by Jesse Liberty
Publisher: O"Reilly
ISBN: 0596003765
*/
using System;
public class MyTimeWithDefaultValue
{
// private member variables
int year;
int month;
int date;
int hour;
int minute;
int second = 30;
// public method
public void DisplayCurrentMyTimeWithDefaultValue()
{
System.Console.WriteLine("{0}/{1}/{2} {3}:{4}:{5}",
month, date, year, hour, minute, second);
}
// constructor
public MyTimeWithDefaultValue(int theYear, int theMonth, int theDate,
int theHour, int theMinute)
{
year = theYear;
month = theMonth;
date = theDate;
hour = theHour;
minute = theMinute;
}
}
public class Tester
{
static void Main()
{
MyTimeWithDefaultValue timeObject = new MyTimeWithDefaultValue(2005,3,25,9,35);
timeObject.DisplayCurrentMyTimeWithDefaultValue();
}
}
declare a class Address containing the data members to describe a US address along with the member functions
using System;
class MainClass {
public static void Main(string[] args) {
Address addr = new Address();
addr.SetStreet(123, "My Street");
addr.SetCity("A", "X", 123456);
Console.WriteLine(addr.GetStreetString());
Console.WriteLine(addr.GetCityString());
addr.Output();
}
}
class Address {
public int nAddressNumberPart;
public string sAddressNamePart;
public string sCity;
public string sState;
public int nPostalCode;
public void SetStreet(int nNumber, string sName) {
nAddressNumberPart = nNumber;
sAddressNamePart = sName;
}
public string GetStreetString() {
return nAddressNumberPart + " " + sAddressNamePart;
}
public void SetCity(string sCityIn, string sStateIn, int nPostalCodeIn) {
sCity = sCityIn;
sState = sStateIn;
nPostalCode = nPostalCodeIn;
}
public string GetCityString() {
return sCity + ", " + sState + " " + nPostalCode;
}
public string GetAddressString() {
return GetStreetString() + "\n" + GetCityString();
}
public void Output() {
Console.WriteLine(GetAddressString());
}
}
Default Values of Class Member Variables
/*
* bool types are set to false.
* Numeric data is set to 0 (or 0.0 in the case of floating-point data types).
* string types are set to null.
* char types are set to "\0".
* Reference types are set to null.
Given these rules, ponder the following code:
*/
class Test
{
public int myInt; // Set to 0.
public string myString; // Set to null.
public bool myBool; // Set to false.
public object myObj; // Set to null.
}
Field Attributes
using System;
using System.Reflection;
public enum RegHives {
HKEY_CLASSES_ROOT,
HKEY_CURRENT_USER,
HKEY_LOCAL_MACHINE,
HKEY_USERS,
HKEY_CURRENT_CONFIG
}
public class RegKeyAttribute : Attribute {
public RegKeyAttribute(RegHives Hive, String ValueName) {
this.Hive = Hive;
this.ValueName = ValueName;
}
protected RegHives hive;
public RegHives Hive {
get { return hive; }
set { hive = value; }
}
protected String valueName;
public String ValueName {
get { return valueName; }
set { valueName = value; }
}
}
class SomeClass {
[RegKey(RegHives.HKEY_CURRENT_USER, "Foo")]
public int Foo;
public int Bar;
}
class Test {
[STAThread]
static void Main(string[] args) {
Type type = Type.GetType("FieldAttribs.SomeClass");
foreach (FieldInfo field in type.GetFields()) {
foreach (Attribute attr in
field.GetCustomAttributes(true)) {
RegKeyAttribute rka =
attr as RegKeyAttribute;
if (null != rka) {
Console.WriteLine("{0} will be saved in {1}\\\\{2}", field.Name, rka.Hive, rka.ValueName);
}
}
}
}
}
Static class variable
/*
Learning C#
by Jesse Liberty
Publisher: O"Reilly
ISBN: 0596003765
*/
using System;
namespace Test_Console_App_3
{
// declare a Cat class
// stripped down
class Cat
{
// a private static member to keep
// track of how many Cat objects have
// been created
private static int instances = 0;
private int weight;
private String name;
// cat constructor
// increments the count of Cats
public Cat(String name, int weight)
{
instances++;
this.name = name;
this.weight = weight;
}
// Static method to retrieve
// the current number of Cats
public static void HowManyCats()
{
Console.WriteLine("{0} cats adopted",
instances);
}
public void TellWeight()
{
Console.WriteLine("{0} is {1} pounds",
name, weight);
}
}
public class StaticInClassTester
{
public void Run()
{
Cat.HowManyCats();
Cat frisky = new Cat("Frisky", 5);
frisky.TellWeight();
Cat.HowManyCats();
Cat whiskers = new Cat("Whisky", 7);
whiskers.TellWeight();
Cat.HowManyCats();
}
static void Main()
{
StaticInClassTester t = new StaticInClassTester();
t.Run();
}
}
}
The super-string class.
using System;
public class MyString {
private string fString;
public MyString() {
fString = "";
}
public MyString(string inStr) {
fString = inStr;
}
public string ToStr() {
return fString;
}
public string Right(int nChars) {
if (nChars > fString.Length)
return fString;
string s = "";
for (int i = fString.Length - nChars; i < fString.Length; ++i)
s += fString[i];
return s;
}
public string Left(int nChars) {
if (nChars > fString.Length)
return fString;
string s = "";
for (int i = 0; i < nChars; ++i)
s += fString[i];
return s;
}
public string Mid(int nStart, int nEnd) {
if (nStart < 0 || nEnd > fString.Length)
return fString;
if (nStart > nEnd)
return "";
string s = "";
for (int i = nStart; i < nEnd; ++i)
s += fString[i];
return s;
}
}
class Class1 {
static void Main(string[] args) {
MyString s = new MyString("Hello world");
System.Console.WriteLine("s = {0}", s.ToStr());
System.Console.WriteLine("Right 3 = [{0}]", s.Right(3));
System.Console.WriteLine("Left 6 = [{0}]", s.Left(6));
System.Console.WriteLine("Mid 2,4 = [{0}]", s.Mid(2, 4));
}
}