【C#】Microsoft C# 视频学习总结

一、文档链接

C# 文档 - 入门、教程、参考。| Microsoft Learn

二、基础学习

1、输出语法

Console.WriteLine()

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){Console.WriteLine("Hello World!");}}
}

Hello World!

2、输出语句中可使用美元符号和花括号写法进行拼接

Console.WriteLine($"{}")

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){String friend = "Kcoff";Console.WriteLine("Hello " + friend);Console.WriteLine($"Hello {friend}");String secondFriend = "Kendra";Console.WriteLine($"My friend are {friend} and {secondFriend}");}}
}

Hello Kcoff
Hello Kcoff
My friend are Kcoff and Kendra

3、字符串长度查询

strName.Length

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){String friend = "Kcoff";Console.WriteLine($"The name {friend} has {friend.Length} letters.");}}
}

The name Kcoff has 5 letters.

4、去除字符串空白符

strName.TrimStart()、strName.TrimEnd()、strName.Trim()

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){String greeting = "      Hello World!     ";// 中括号的作用：可视化空白Console.WriteLine($"[{greeting}]");Console.WriteLine($"***{greeting}***");String trimmedGreeting = greeting.TrimStart();Console.WriteLine($"[{trimmedGreeting}]");trimmedGreeting = greeting.TrimEnd();Console.WriteLine($"[{trimmedGreeting}]");trimmedGreeting = greeting.Trim();Console.WriteLine($"[{trimmedGreeting}]");}}
}

[      Hello World!     ]
***      Hello World!     ***
[Hello World!     ]
[      Hello World!]
[Hello World!]

5、字符串替换

strName.Replace(source, target)

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){String sayHello = "Hello World!";Console.WriteLine(sayHello);sayHello = sayHello.Replace("Hello", "Greetings");Console.WriteLine(sayHello);}}
}

Hello World!
Greetings World!

6、字符串大小写转换

strName.ToUpper()、strName.ToLower()

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){String sayHello = "Hello World!";Console.WriteLine(sayHello.ToUpper());Console.WriteLine(sayHello.ToLower());}}
}

HELLO WORLD!
hello world!

7、字符串是否包含什么、是否以什么为开头、是否以什么为结尾

strName.Contains(target)、strName.StartsWith(target)、strName.EndsWith(target)

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){String songLyrics = "You say goodbye, and I say hello";var result = songLyrics.Contains("goodbye");Console.WriteLine(result);Console.WriteLine(songLyrics.Contains("greetings"));var result2 = songLyrics.StartsWith("You");Console.WriteLine(result2);Console.WriteLine(songLyrics.StartsWith("goodbye"));var result3 = songLyrics.EndsWith("hello");Console.WriteLine(result3);Console.WriteLine(songLyrics.EndsWith("goodbye"));}}
}

True
False
True
False
True
False

8、计算

1、加减乘除

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){int a = 18;int b = 6;int c = a + b;Console.WriteLine(c);int d = a - b;Console.WriteLine(d);int e = a * b;Console.WriteLine(e);int f = a / b;Console.WriteLine(f);}}
}

2、计算顺序

优先计算括号里面的计算，之后先算乘除后算加减

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){int a = 5;int b = 4;int c = 2;int d = a + b * c;Console.WriteLine(d);int e = (a + b) * c;Console.WriteLine(e);int f = (a + b) - 6 * c + (12 * 4) / 3 + 12;Console.WriteLine(f);}}
}

13
18
25

3、除法只保留整数部分

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){int a = 7;int b = 4;int c = 3;int d = (a + b) / c;Console.WriteLine(d);}}
}

4、取余数

被除数 % 除数

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){int a = 7;int b = 4;int c = 3;int d = (a + b) / c;int e = (a + b) % c;// 商Console.WriteLine($"quotient: {d}");// 余数Console.WriteLine($"remainder: {e}");}}
}

quotient: 3
remainder: 2

9、类型（最大值、最小值及部分计算）

1、int

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){int max = int.MaxValue;int min = int.MinValue;Console.WriteLine($"The range of integers type is {min} to {max}");int what = max + 3;Console.WriteLine($"An example of overflow: {what}");}}
}

The range of integers type is -2147483648 to 2147483647
An example of overflow: -2147483646

2、double

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){double max = double.MaxValue;double min = double.MinValue;Console.WriteLine($"The range of double type is {min} to {max}");}}
}

The range of double type is -1.79769313486232E+308 to 1.79769313486232E+308

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){double a = 5;double b = 4;double c = 2;double d = (a + b) / c;Console.WriteLine(d);a = 19;b = 23;c = 8;double e = (a + b) / c;Console.WriteLine(e);double third = 1.0 / 3.0;Console.WriteLine(third);}}
}

4.5
5.25
0.333333333333333

3、decimal

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){decimal max = decimal.MaxValue;decimal min = decimal.MinValue;Console.WriteLine($"The range of decimal type is {min} to {max}");}}
}

The range of decimal type is -79228162514264337593543950335 to 79228162514264337593543950335

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){double a = 1.0;double b = 3.0;Console.WriteLine(a / b);decimal c = 1.0M;decimal d = 3.0M;Console.WriteLine(c / d);}}
}

0.333333333333333
0.3333333333333333333333333333

4、long

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){long max = long.MaxValue;long min = long.MinValue;Console.WriteLine($"The range of long type is {min} to {max}");}}
}

The range of long type is -9223372036854775808 to 9223372036854775807

5、short

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){short max = short.MaxValue;short min = short.MinValue;Console.WriteLine($"The range of short type is {min} to {max}");}}
}

The range of short type is -32768 to 32767

10、圆的面积

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){double radius = 2.50;double area = Math.PI * radius * radius;Console.WriteLine(area);}}
}

19.634954084936208

11、if-else 语句

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){int a = 5;int b = 6;bool something = a + b > 10;if (something)Console.WriteLine("The answer is greater then 10");}}
}

The answer is greater then 10

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){int a = 5;int b = 3;bool something = a + b > 10;if (something){Console.WriteLine("The answer is greater then 10");}else{Console.WriteLine("The answer is not greater then 10");}}}
}

The answer is not greater then 10

12、&& 和 ||

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){int a = 5;int b = 3;int c = 4;if ((a + b + c > 10) && (a == b)){Console.WriteLine("The answer is greater then 10");Console.WriteLine("And the first number is equal to the second");}else{Console.WriteLine("The answer is not greater then 10");Console.WriteLine("Or the first number is not equal to the second");}}}
}

The answer is not greater then 10
Or the first number is not equal to the second

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){int a = 5;int b = 3;int c = 4;if ((a + b + c > 10) || (a == b)){Console.WriteLine("The answer is greater then 10");Console.WriteLine("And the first number is equal to the second");}else{Console.WriteLine("The answer is not greater then 10");Console.WriteLine("Or the first number is not equal to the second");}}}
}

The answer is greater then 10
And the first number is equal to the second

13、while 语句

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){int counter = 0;while (counter < 10){Console.WriteLine($"Hello World! The counter is {counter}");counter++;}}}
}

Hello World! The counter is 0
Hello World! The counter is 1
Hello World! The counter is 2
Hello World! The counter is 3
Hello World! The counter is 4
Hello World! The counter is 5
Hello World! The counter is 6
Hello World! The counter is 7
Hello World! The counter is 8
Hello World! The counter is 9

14、do-while 语句

和 while 语句的区别是至少会执行一次操作

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){int counter = 10;// 至少执行一次操作do{Console.WriteLine($"Hello World! The counter is {counter}");counter++;} while (counter < 10);}}
}

Hello World! The counter is 10

15、for 语句

1、写法

执行顺序：int index = 0 -> index < 10 -> Console.WriteLine() -> index++

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){for (int index = 0; index < 10; index++){Console.WriteLine($"Hello World! The index is {index}");}}}
}

Hello World! The index is 0
Hello World! The index is 1
Hello World! The index is 2
Hello World! The index is 3
Hello World! The index is 4
Hello World! The index is 5
Hello World! The index is 6
Hello World! The index is 7
Hello World! The index is 8
Hello World! The index is 9

2、求 1~20 中能被 3 整除的数的总和

using System;
namespace HelloWorldApplication
{class HelloWorld{static void Main(string[] args){int sum = 0;for (int i = 1; i <= 20; i++) {if (i % 3 == 0){sum = sum + i;}}Console.WriteLine($"The sum is {sum}");}}
}

The sum is 63

16、Arrays、List、Collections

1、输出

foreach、for

using System;
using System.Collections.Generic;namespace ConsoleApp
{class Program{static void Main(string[] args){var names = new List<string> { "Scott", "Kendra" };foreach (var name in names){Console.WriteLine($"Hello {name.ToUpper()}!");}for (int i = 0; i < names.Count; i++){Console.WriteLine($"Hello {names[i].ToUpper()}!");}}}
}

Hello SCOTT!
Hello KENDRA!
Hello SCOTT!
Hello KENDRA!

2、新增或删除

list.Add(source)、list.Remove(source)

using System;
using System.Collections.Generic;namespace ConsoleApp
{class Program{static void Main(string[] args){var names = new List<string> { "Scott", "Kendra" };names.Add("Maria");names.Add("Bill");names.Remove("Scott");foreach (var name in names){Console.WriteLine(name);}Console.WriteLine(names[1]);}}
}

Kendra
Maria
Bill
Maria

3、索引

list.IndexOf(target)

using System;
using System.Collections.Generic;namespace ConsoleApp
{class Program{static void Main(string[] args){var names = new List<string> { "WEIRD", "Scott", "Kendra" };names.Add("Maria");names.Add("Bill");names.Remove("Scott");foreach (var name in names){Console.WriteLine(name);}var index = names.IndexOf("Kendra");if (index != -1){Console.WriteLine($"When an item is not found, IndexOf returns {index}");}else{Console.WriteLine($"The name {names[index]} is at index {index}");}}}
}

WEIRD
Kendra
Maria
Bill
When an item is not found, IndexOf returns 1

4、排序

list.Sort()

using System;
using System.Collections.Generic;namespace ConsoleApp
{class Program{static void Main(string[] args){var names = new List<string> { "New Friend", "Scott", "Kendra" };names.Add("Maria");names.Add("Bill");foreach (var name in names){Console.WriteLine(name);}Console.WriteLine();names.Sort();foreach (var name in names){Console.WriteLine(name);}}}
}

New Friend
Scott
Kendra
Maria
BillBill
Kendra
Maria
New Friend
Scott

5、斐波那契数列

using System;
using System.Collections.Generic;namespace ConsoleApp
{class Program{static void Main(string[] args){var fibonacciNumbers = new List<int> { 1, 1 };while (fibonacciNumbers.Count < 20){var previous = fibonacciNumbers[fibonacciNumbers.Count - 1];var previous2 = fibonacciNumbers[fibonacciNumbers.Count - 2];fibonacciNumbers.Add(previous + previous2);}foreach (var item in fibonacciNumbers){Console.WriteLine(item);}}}
}

17、面向对象

1、模拟银行创建用户并存钱

using System;namespace ConsoleApp
{public class BankAccount{public string Number { get; }public string Owner { get; set; }public decimal Balance { get; }public BankAccount(string name, decimal initialBalance){this.Owner = name;this.Balance = initialBalance;}public void MakeDeposit(decimal amount, DateTime date, string note){}public void MakeWithdrawal(decimal amount, DateTime date, string note){}}
}

using System;namespace ConsoleApp
{class Program{static void Main(string[] args){var account = new BankAccount("Kendra", 10000);Console.WriteLine($"Account {account.Number} was created for {account.Owner} with {account.Balance}");}}
}

Account  was created for Kendra with 10000

2、模拟银行存款取款

using System;namespace ConsoleApp
{public class Transaction{public decimal Amount { get; }public DateTime Date { get; }public string Notes { get; }public Transaction(decimal amount, DateTime date, string note){this.Amount = amount;this.Date = date;this.Notes = note;}}
}

using System;
using System.Collections.Generic;namespace ConsoleApp
{public class BankAccount{public string Number { get; }public string Owner { get; set; }public decimal Balance{ get{decimal balance = 0;foreach (var item in allTransactions){balance += item.Amount;}return balance;}}private static int accountNumberSeed = 1234567890;private List<Transaction> allTransactions = new List<Transaction>();public BankAccount(string name, decimal initialBalance){this.Owner = name;MakeDeposit(initialBalance, DateTime.Now, "Initial Balance");this.Number = accountNumberSeed.ToString();accountNumberSeed++;}// 存款public void MakeDeposit(decimal amount, DateTime date, string note){if (amount <= 0){throw new ArgumentOutOfRangeException(nameof(amount), "Amount of deposit must be positive");}var deposit = new Transaction(amount, date, note);allTransactions.Add(deposit);}// 取款public void MakeWithdrawal(decimal amount, DateTime date, string note){if (amount <= 0){throw new ArgumentOutOfRangeException(nameof(amount), "Amount of deposit must be positive");}if (Balance - amount < 0){throw new InvalidOperationException("Not sufficient funds for this withdrawal");}var withdrawal = new Transaction(-amount, date, note);allTransactions.Add(withdrawal);}}
}

using System;namespace ConsoleApp
{class Program{static void Main(string[] args){var account = new BankAccount("Kendra", 10000);Console.WriteLine($"Account {account.Number} was created for {account.Owner} with {account.Balance}");account.MakeWithdrawal(120, DateTime.Now, "Hammock");Console.WriteLine(account.Balance);}}
}

Account 1234567890 was created for Kendra with 10000
9880

3、存取款异常处理

using System;namespace ConsoleApp
{class Program{static void Main(string[] args){var account = new BankAccount("Kendra", 10000);Console.WriteLine($"Account {account.Number} was created for {account.Owner} with {account.Balance}");account.MakeWithdrawal(120, DateTime.Now, "Hammock");Console.WriteLine(account.Balance);account.MakeWithdrawal(50, DateTime.Now, "Xbox Game");Console.WriteLine(account.Balance);// hey this is a comment// Test for a negative balancetry{account.MakeWithdrawal(75000, DateTime.Now, "Attempt to overdraw");}catch (InvalidOperationException e){Console.WriteLine("Exception caught trying to overdraw");Console.WriteLine(e.ToString());}// Test that the initial balances must be posttivetry{var invalidAccount = new BankAccount("invalid", -55);}catch (ArgumentOutOfRangeException e){Console.WriteLine("Exception caught creating account with negative balance");Console.WriteLine(e.ToString());}}}
}

Account 1234567890 was created for Kendra with 10000
9880
9830
Exception caught trying to overdraw
System.InvalidOperationException: Not sufficient funds for this withdrawalat ConsoleApp.BankAccount.MakeWithdrawal(Decimal amount, DateTime date, String note) in F:\CSharpRepository\ConsoleApp\ConsoleApp\BankAccount.cs:line 58at ConsoleApp.Program.Main(String[] args) in F:\CSharpRepository\ConsoleApp\ConsoleApp\Program.cs:line 24
Exception caught creating account with negative balance
System.ArgumentOutOfRangeException: Amount of deposit must be positive (Parameter 'amount')at ConsoleApp.BankAccount.MakeDeposit(Decimal amount, DateTime date, String note) in F:\CSharpRepository\ConsoleApp\ConsoleApp\BankAccount.cs:line 44at ConsoleApp.BankAccount..ctor(String name, Decimal initialBalance) in F:\CSharpRepository\ConsoleApp\ConsoleApp\BankAccount.cs:line 32at ConsoleApp.Program.Main(String[] args) in F:\CSharpRepository\ConsoleApp\ConsoleApp\Program.cs:line 35

4、账户交易历史记录

using System;
using System.Collections.Generic;
using System.Text;namespace ConsoleApp
{public class BankAccount{public string Number { get; }public string Owner { get; set; }public decimal Balance{ get{decimal balance = 0;foreach (var item in allTransactions){balance += item.Amount;}return balance;}}private static int accountNumberSeed = 1234567890;private List<Transaction> allTransactions = new List<Transaction>();public BankAccount(string name, decimal initialBalance){this.Owner = name;MakeDeposit(initialBalance, DateTime.Now, "Initial Balance");this.Number = accountNumberSeed.ToString();accountNumberSeed++;}public void MakeDeposit(decimal amount, DateTime date, string note){if (amount <= 0){throw new ArgumentOutOfRangeException(nameof(amount), "Amount of deposit must be positive");}var deposit = new Transaction(amount, date, note);allTransactions.Add(deposit);}public void MakeWithdrawal(decimal amount, DateTime date, string note){if (amount <= 0){throw new ArgumentOutOfRangeException(nameof(amount), "Amount of deposit must be positive");}if (Balance - amount < 0){throw new InvalidOperationException("Not sufficient funds for this withdrawal");}var withdrawal = new Transaction(-amount, date, note);allTransactions.Add(withdrawal);}public string GetAccountHistory(){var report = new StringBuilder();// HEADERreport.AppendLine("Date\t\tAmount\tNote");foreach (var item in allTransactions){// ROWSreport.AppendLine($"{item.Date.ToShortDateString()}\t{item.Amount}\t{item.Notes}");}return report.ToString();}}
}

using System;namespace ConsoleApp
{class Program{static void Main(string[] args){var account = new BankAccount("Kendra", 10000);Console.WriteLine($"Account {account.Number} was created for {account.Owner} with {account.Balance}");account.MakeWithdrawal(120, DateTime.Now, "Hammock");account.MakeWithdrawal(50, DateTime.Now, "Xbox Game");Console.WriteLine(account.GetAccountHistory());}}
}

Account 1234567890 was created for Kendra with 10000
Date            Amount  Note
2023/12/12      10000   Initial Balance
2023/12/12      -120    Hammock
2023/12/12      -50     Xbox Game