const 与 readonly的差别

using System;

class clsa
{
    public readonly int b;
    public clsa()
    {
        b = 200;   //可以在构造函数中赋值
    }
    
}

class Program {
    const int a = 100; //必须定义的时候就赋值
   
    static void Main(string[] args) {
      
    
        Console.WriteLine($"a = {a}");
    
        
        clsa a1 = new clsa();
        //a1.b = 1; //不能再赋值了
        Console.WriteLine($"{a1.b}");
    }
}