不知道到底错在哪里，为什么n++无效。

Question

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace 猜数字
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Box1_TextChanged(object sender, EventArgs e)
        {
        }

        private void btn_Click(object sender, EventArgs e)
        {
            int rndint = 50;
            int n=0;
            while (true)
            {
                    if (Convert.ToInt32(Box1.Text) > rndint)
                    {
                        Label3.Text = ("第" + n + "次，大了");
                        n++;
                       return;
                    }
                    else if (Convert.ToInt32(Box1.Text) < rndint)
                    {
                        Label3.Text = ("第" + n + "次，小了");
                        n++;
                        return;
                    }
                    else if (Convert.ToInt32(Box1.Text) == rndint)
                    {
                        Label3.Text = ("恭喜你，猜中了！共尝试了" + n + "次");
                        break;
                    }
            }
                DialogResult result;
                result = MessageBox.Show("再玩一次？","猜数字小游戏", MessageBoxButtons.YesNo);
                if (result == DialogResult.Yes)
                {
                      return;
                }
                else
                {
                   Application.Exit();
                }
        }
    }
}

Answer 1

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace 猜数字
{
    public partial class Form1 : Form
    {
        int n=0;
        public Form1()
        {
            InitializeComponent();
        }
        private void Box1_TextChanged(object sender, EventArgs e)
        {
        }
        private void btn_Click(object sender, EventArgs e)
        {
            int rndint = 50;
            
            while (true)
            {
                    if (Convert.ToInt32(Box1.Text) > rndint)
                    {
                        Label3.Text = ("第" + n + "次，大了");
                        n++;
                       return;
                    }
                    else if (Convert.ToInt32(Box1.Text) < rndint)
                    {
                        Label3.Text = ("第" + n + "次，小了");
                        n++;
                        return;
                    }
                    else if (Convert.ToInt32(Box1.Text) == rndint)
                    {
                        Label3.Text = ("恭喜你，猜中了！共尝试了" + n + "次");
                        break;
                    }
            }
                DialogResult result;
                result = MessageBox.Show("再玩一次？","猜数字小游戏", MessageBoxButtons.YesNo);
                if (result == DialogResult.Yes)
                {
                      n=0;
                      return;
                }
                else
                {
                   Application.Exit();
                }
        }
    }
}

n应该设置成全局变量。