标签：Console c# 笔记 class -- int WriteLine new public
C#基础
c#集合--Collections
来源：TestAutomation.CSharp.Basics/CSharp.Collections/Collections/Collections_Dictionaries.cs
Arrays集合
创建：
// defining array with size 5.
// But not assigns values
int[] intArray1 = new int[5];
// defining array with size 5 and assigning
// values at the same time
int[] intArray2 = new int[5] { 1, 2, 3, 4, 5 };
更新：
string[] cars = { "Volvo", "BMW", "Ford", "Mazda" };
cars[0] = "Opel";
Console.WriteLine(cars[0]);
输出：
// Accessing array values using for loop
for (int i = 0; i < intArray3.Length; i++)
Console.WriteLine(" " + intArray3[i]);
// Accessing array values using foreach loop
foreach (int i in intArray3)
Console.WriteLine(" " + i);
排序：
int[] myNumbers = { 5, 1, 8, 9 };
Array.Sort(myNumbers);
Dictionary集合
创建c#集合：
方法一
IDictionary<int, string> numberNames = new Dictionary<int, string>();
numberNames.Add(1, "One"); //adding a key/value using the Add() method
numberNames.Add(2, "Two");
numberNames.Add(3, "Three");
方法二
//creating a dictionary using collection-initializer syntax
var cities = new Dictionary<string, string>(){
{"UK", "London, Manchester, Birmingham"},
{"USA", "Chicago, New York, Washington"},
{"India", "Mumbai, New Delhi, Pune"}
};
遍历Dictionary集合：
foreach (KeyValuePair<int, string> kvp in numberNames)
Console.WriteLine("Key: {0}, Value: {1}", kvp.Key, kvp.Value);
输出集合内容：
Console.WriteLine(cities["UK"]); //prints value of UK key
查询集合所含键：
//use ContainsKey() to check for an unknown key
if (cities.ContainsKey("France"))
{
Console.WriteLine(cities["France"]);
}
//use TryGetValue() to get a value of unknown key
string result;
if (cities.TryGetValue("France", out result))
{
Console.WriteLine(result);
}
//use ElementAt() to retrieve key-value pair using index
for (int i = 0; i < cities.Count; i++)
{
Console.WriteLine("Key: {0}, Value: {1}",
cities.ElementAt(i).Key,
cities.ElementAt(i).Value);
}
删除集合内容：
if (cities.ContainsKey("France"))
{ // check key before removing it
cities.Remove("France");
}
cities.Clear(); //removes all elements
Hashtable集合
创建：
Hashtable numberNames = new Hashtable();
numberNames.Add(1, "One"); //adding a key/value using the Add() method
//creating a Hashtable using collection-initializer syntax
var cities = new Hashtable(){
{"UK", "London, Manchester, Birmingham"},
{"USA", "Chicago, New York, Washington"},
{"India", "Mumbai, New Delhi, Pune"}
};
遍历：
foreach (DictionaryEntry de in numberNames)
Console.WriteLine("Key: {0}, Value: {1}", de.Key, de.Value);
删除
if (cities.ContainsKey("France"))
{ // check key before removing it
cities.Remove("France");
}
cities.Clear(); //removes all elements
List集合
创建：
List<int> primeNumbers = new List<int>();
primeNumbers.Add(1); // adding elements using add() method
primeNumbers.Add(3);
var cities = new List<string>();
cities.Add("New York");
cities.Add("London");
//adding elements using collection-initializer syntax
var bigCities = new List<string>()
{
"New York",
"London",
"Mumbai",
"Chicago"
};
var students = new List<Student>() {
new Student(){ Id = 1, Name="Bill"},
new Student(){ Id = 2, Name="Steve"},
new Student(){ Id = 3, Name="Ram"},
new Student(){ Id = 4, Name="Abdul"}
};
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
}
查询：
var numbers = new List<int>() { 10, 20, 30, 40 };
Assert.IsTrue(numbers.Contains(10)); // returns true
输出：
List<int> numbers = new List<int>() { 1, 2, 5, 7, 8, 10 };
Console.WriteLine(numbers[0]); // prints 1
// using foreach LINQ method
numbers.ForEach(num => Console.WriteLine(num + ", "));//prints 1, 2, 5, 7, 8, 10,
// using for loop
for (int i = 0; i < numbers.Count; i++)
Console.WriteLine(numbers[i]);
//get all students whose name is Bill
var result = from s in students
where s.Name == "Bill"
select s;
foreach (var student in result)
Console.WriteLine(student.Id + ", " + student.Name);
插入：
var numbers = new List<int>() { 10, 20, 30, 40 };
numbers.Insert(1, 11);// inserts 11 at 1st index: after 10.
删除：
var numbers = new List<int>() { 10, 20, 30, 40, 10 };
numbers.Remove(10); // removes the first 10 from a list
numbers.RemoveAt(2); //removes the 3rd element (index starts from 0)
//numbers.RemoveAt(10); //throws ArgumentOutOfRangeException
SortedList:
类似于Dictionary
public void Lists_SortedLists()
{
SortedList<string, string> cities = new SortedList<string, string>()
{
{"London", "UK"},
{"New York", "USA"},
{ "Mumbai", "India"},
{"Johannesburg", "South Africa"}
};
foreach (KeyValuePair<string, string> kvp in cities)
Console.WriteLine("key: {0}, value: {1}", kvp.Key, kvp.Value);
}
面向对象：
类
public class MyClass
{
// Data member/ field
public string myField = string.Empty;
public string constructorField = string.Empty;
// Constructor
public MyClass()
{
constructorField = "Initialised when object is created";
}
// Method
public string MyMethod(int parameter1, string parameter2)
{
string myString = ($"First Parameter {parameter1}, second parameter {parameter2}");
Console.WriteLine(myString);
return myString;
}
// Property
public int MyAutoImplementedProperty { get; set; }
private string myPropertyVar;
// Custom Property
public string MyProperty
{
get { return myPropertyVar; }
set { myPropertyVar = value; }
}
}
}
继承
// Base class
class base_Shape
{
protected int width;
protected int height;
protected int radius;
public void setWidth(int w)
{
width = w;
}
public void setHeight(int h)
{
height = h;
}
public void setRadius(int r)
{
radius = r;
}
}
// Derived class
class derived_Rectangle : base_Shape
{
public int getArea()
{
return (width * height);
}
}
// Derived class
class derived_Circle : base_Shape
{
public double getArea()
{
return (3.14 * radius * radius);
}
}
抽象类：
using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Abstraction;
namespace CSharp.OOPs.OOPs
{
[TestClass]
public class OOPs_Abstraction
{
[TestMethod]
public void OOPs_AbstractionImplementation()
{
Rectangle r = new Rectangle(10, 7);
double a = r.area();
Console.WriteLine("Area: {0}", a);
Assert.AreEqual(70, r.area());
}
}
}
namespace Abstraction
{
abstract class Shape
{
public abstract int area();
}
class Rectangle : Shape
{
private int length;
private int width;
public Rectangle(int a = 0, int b = 0)
{
length = a;
width = b;
}
public override int area()
{
Console.WriteLine("Rectangle class area :");
return (width * length);
}
}
}
多态
网址:https://docs.microsoft.com/zh-cn/dotnet/csharp/fundamentals/object-oriented/polymorphism
1）运行时派生类被视为基类
2）通过派生类重写基类的虚方法实现多态
public class Shape
{
// A few example members
public int X { get; private set; }
public int Y { get; private set; }
public int Height { get; set; }
public int Width { get; set; }
// Virtual method
public virtual void Draw()
{
Console.WriteLine("Performing base class drawing tasks");
}
}
public class Circle : Shape
{
public override void Draw()
{
// Code to draw a circle...
Console.WriteLine("Drawing a circle");
base.Draw();
}
}
public class Rectangle : Shape
{
public override void Draw()
{
// Code to draw a rectangle...
Console.WriteLine("Drawing a rectangle");
base.Draw();
}
}
public class Triangle : Shape
{
public override void Draw()
{
// Code to draw a triangle...
Console.WriteLine("Drawing a triangle");
base.Draw();
}
}
3）通过"foreach "遍历派生类
var shapes = new List<Shape>
{
new Rectangle(),
new Triangle(),
new Circle()
};
// Polymorphism at work #2: the virtual method Draw is
// invoked on each of the derived classes, not the base class.
foreach (var shape in shapes)
{
shape.Draw();
}
4）虚方法的覆盖：
a. 派生类可以覆盖基类中的虚拟成员，定义新的行为。
b. 派生类继承最近的基类方法而不覆盖它，保留现有行为但允许进一步的派生类覆盖该方法。
c. 派生类可以定义那些隐藏基类实现的成员的新的非虚拟实现
5）用新成员隐藏基类成员
new 关键字覆盖虚方法
public class BaseClass
{
public void DoWork() { WorkField++; }
public int WorkField;
public int WorkProperty
{
get { return 0; }
}
}
public class DerivedClass : BaseClass
{
public new void DoWork() { WorkField++; }
public new int WorkField;
public new int WorkProperty
{
get { return 0; }
}
}
强制向上转型，调用基类方法
DerivedClass B = new DerivedClass();
B.DoWork(); // Calls the new method.
BaseClass A = (BaseClass)B;
A.DoWork(); // Calls the old method.
6）防止派生类覆盖虚拟成员
在类成员声明中将sealed 关键字放在override 关键字之前。
public class C : B
{
public sealed override void DoWork() { }
}
8）从派生类访问基类虚拟成员
public class Base
{
public virtual void DoWork() {/*...*/ }
}
public class Derived : Base
{
public override void DoWork()
{
//Perform Derived's work here
//...
// Call DoWork on base class
base.DoWork();
}
}
使用:
public void OOPs_Polymorhism_Dynamic()
{
Caller c = new Caller();
Rectangle r = new Rectangle(10, 7);
Triangle t = new Triangle(10, 5);
c.CallArea(r);
Assert.AreEqual(70, c.CallArea(r));
c.CallArea(t);
Assert.AreEqual(25, c.CallArea(t));
}
接口
namespace TestAutomation.CSharp.OOPs
{
interface IFile
{
void ReadFile();
void WriteFile(string text);
}
}
public class FileInfo : IFile
{
public void ReadFile()
{
Console.WriteLine("Reading File");
}
public void WriteFile(string text)
{
Console.WriteLine("Writing to file");
}
public void InterfaceImplement()
{
IFile file1 = new FileInfo();
FileInfo file2 = new FileInfo();
file1.ReadFile();
file1.WriteFile("content");
file2.ReadFile();
file2.WriteFile("content");
}
}
数据类型
显示转换
int num1 = 10;
int num2 = 4;
double num3 = (double)num1 / num2;
int num1 = 10;
int num2 = 4;
double num3 = Convert.ToDouble(num1) / Convert.ToDouble(num2);
var checkFalse = Convert.ToBoolean(2 - 2);
decimal decimalVal;
string stringVal = "2,345.26";
decimalVal = Convert.ToDecimal(stringVal);
string dateString = "05/01/1996";
ConvertToDateTime(dateString);
//日期转换
string dateString = "05/01/1996";
ConvertToDateTime(dateString);
private static void ConvertToDateTime(string value)
{
DateTime convertedDate;
try
{
convertedDate = Convert.ToDateTime(value);
Console.WriteLine("'{0}' converts to {1} {2} time.",
value, convertedDate,
convertedDate.Kind.ToString());
}
catch (FormatException)
{
Console.WriteLine("'{0}' is not in the proper format.", value);
}
}
隐式转换
由 C# 以类型安全的方式执行。例如，从较小到较大的整数类型的转换以及从派生类到基类的转换
int num1 = 10;
double num2 = 15.8;
var num3 = num1 + num2;//num3 == 25.8
int num1 = 10;
int num2 = 4;
double num3 = num1 / num2;//num3 == 2
int age = 30;
Console.WriteLine($"My age is {age}");//My age is 30
标签：Console,c#,笔记,class,--,int,WriteLine,new,public 来源： https://www.cnblogs.com/dongdongtest/p/15614790.html
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