编辑代码

using System;

public class HelloWorld
{
    public static void Main()
    {
       //程序运行完成时一定要有输出语句，本工具才能正确展示运行结果。
        Console.WriteLine("HELLO JSRUN     - from C# ");
    }

    public void Method1()
    {
        string str = "";
        for(int i = 0; i < 100; i++)
        {
            str += "test" + i;
        }
    }

    public void Method2()
    {
        string str = string.Format("{0},{1},{2}", "testA", "testB", "testC");
    }

    public void Method3()
    {
        StringBuilder str = new StringBuilder();
        for (int i = 0; i < 100; i++)
        {
            str.Append("test" + i);
        }
    }
    
    public void Method4()
        {
            var a0 = "User";
            var a1 = "Id";
            var a2 = 10086;
            var str = $"select * from {a0} where {a1}={a2}";
        }

}