我刚开始学习 C# 并开始使用 Windows Forms 项目。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，并且找不到接受“Downloader.SDownloader”类型的第一个参数的扩展方法“errorProvider1”（您是否缺少 using 指令或程序集引用？） 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) {
}
}
}
