errorProvider1不包含定义，也没有扩展方法

Question

我刚开始学习C＃并从Windows Forms项目开始。 当我尝试验证文本字段时，我收到此错误：

  

错误1'Downloader.SDownloader'不包含'errorProvider1'的定义，并且没有扩展方法'errorProvider1'接受类型'Downloader.SDownloader'的第一个参数'（你是否缺少using指令或程序集）参考？）C：\ Users \ Bad_Wolf \ documents \ visual studio 2010 \ Projects \ Register \ Register \ Form1.cs 77 22注册

有我的源代码：

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

namespace Downloader {
    public partial class SDownloader : Form {
        public SDownloader() {
            InitializeComponent();
        }
        private void fname_MouseClick(object sender, MouseEventArgs e) {
           fname.Text = "";
        }
        private void fname_TextChanged(object sender, EventArgs e) {

        }
        private void lname_MouseClick(object sender, MouseEventArgs e) {
            lname.Text = "";
        }
        private void lname_TextChanged(object sender, EventArgs e) {

        }
        private void username_MouseClick(object sender, MouseEventArgs e) {
            username.Text = "";
        }
        private void email_MouseClick(object sender, MouseEventArgs e) {
            email.Text = "";
        }
        private void password_MouseClick(object sender, MouseEventArgs e) {
            password.Text = "";
        }
        private void password2_MouseClick(object sender, MouseEventArgs e) {
            password2.Text = "";
        }
        private void password2_TextChanged(object sender, EventArgs e) {

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

        }
        private void fname_Validating(object sender, CancelEventArgs e) {
            string errorMsg;
            if (fname.Text.Trim().Length < 4) {
                e.Cancel = true;
                fname.Select(0, fname.Text.Length);
                this.errorProvider1.SetError(fname, errorMsg);
            }
        }
        private void fname_Validated(object sender, EventArgs e) {

        }
    }
}

Answer 1

您收到此错误的原因是您尚未在设计视图中将ErrorProvider添加到表单中。添加ErrorProvider并将其命名为errorProvider1