Form1.cs

这里只显示每个文件的开头 60 行。登录后可以解锁完整代码。

微信扫码关注公众号，代码整理好后第一时间通知你。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
// 下载于www.51aspx.com
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "")
            {
                button3.Text = "商品名称不能为空";
                button3.ForeColor = Color.Red;
                textBox1.Focus();
            }
            else
            {
                if (listBox1.Items.Count > 0)
                {
                    for (int i = 0; i < listBox1.Items.Count; i++)
                    {
                        if (listBox1.Items[i].ToString() == textBox1.Text)
                        {
                            button3.Text = "商品已存在";
                            button3.ForeColor = Color.Red;
                            textBox1.Clear();
                            textBox1.Focus();
                            
                        }
                    }
                    //listBox1.Items.Add(textBox1.Text);
                    //textBox1.Clear();
                }
                listBox1.Items.Add(textBox1.Text);
                textBox1.Clear();
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
        }

        //private void button4_Click(object sender, EventArgs e)
        //{

        //}