C# 中的 switch
语句支持以下几种类型:
- 字符串(string):这是最常用的
switch
类型,可以对字符串进行比较。
string input = "apple"; switch (input) { case "apple": Console.WriteLine("It's an apple."); break; case "banana": Console.WriteLine("It's a banana."); break; default: Console.WriteLine("Unknown fruit."); break; }
- 整数(int、short、byte、sbyte):可以对整数进行比较,支持范围检查。
int number = 2; switch (number) { case 1: Console.WriteLine("Number is one."); break; case 2: Console.WriteLine("Number is two."); break; case 3: Console.WriteLine("Number is three."); break; default: Console.WriteLine("Number is not 1, 2, or 3."); break; }
- 枚举(enum):可以对枚举值进行比较。
enum Color { Red, Green, Blue } Color color = Color.Red; switch (color) { case Color.Red: Console.WriteLine("Color is red."); break; case Color.Green: Console.WriteLine("Color is green."); break; case Color.Blue: Console.WriteLine("Color is blue."); break; default: Console.WriteLine("Unknown color."); break; }
- 布尔值(bool):可以对布尔值进行比较。
bool isRaining = true; switch (isRaining) { case true: Console.WriteLine("It's raining."); break; case false: Console.WriteLine("It's not raining."); break; default: Console.WriteLine("Unknown weather."); break; }
- 字节(byte)、短整型(short)、长整型(long):这些数值类型也可以用于
switch
语句。
byte value = https://www.yisu.com/ask/1;"Value is one."); break; case 2: Console.WriteLine("Value is two."); break; default: Console.WriteLine("Value is not 1 or 2."); break; }
- 自定义类型:通过实现
IEquatable
接口和重写Equals()
方法,自定义类型也可以用于switch
语句。
public class Person
{
public string Name { get; set; }
public override bool Equals(object obj)
{
if (obj == null || GetType() != obj.GetType())
return false;
Person person = (Person)obj;
return string.Equals(Name, person.Name);
}
public override int GetHashCode()
{
return Name.GetHashCode();
}
}
Person person = new Person { Name = "Alice" };
switch (person)
{
case Person p when p.Name == "Alice":
Console.WriteLine("It's Alice.");
break;
case Person p when p.Name == "Bob":
Console.WriteLine("It's Bob.");
break;
default:
Console.WriteLine("Unknown person.");
break;
}