我正在为网页上的文本框添加价值。 这是Inspect Element代码：
<input type="text" name="DERIVED_LAM_GRADE_1$0" id="DERIVED_LAM_GRADE_1$0"
tabindex="90" value="0.00" class="PSEDITBOX" style="width:44px;
text-align:right; " maxlength="6" onchange="addchg_win0(this);oChange_win0=this;">
这是我的C＃代码： 这给了我异常＆＃34;对象引用未设置为对象的实例。＆＃34;
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;
namespace WindowsFormsApplication2
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
string username = textBox1.Text;
HtmlDocument doc = this.webBrowser1.Document;
doc.GetElementById("DERIVED_LAM_GRADE_1$0").SetAttribute("value", username);
}
}
}
我不知道什么是错的。我给了一个完美的身份，但仍然是它的抛出异常。
设计师代码：
namespace WindowsFormsApplication2
{
partial class Form1
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.webBrowser1 = new System.Windows.Forms.WebBrowser();
this.splitContainer1 = new System.Windows.Forms.SplitContainer();
this.button1 = new System.Windows.Forms.Button();
this.label2 = new System.Windows.Forms.Label();
this.label1 = new System.Windows.Forms.Label();
this.textBox2 = new System.Windows.Forms.TextBox();
this.textBox1 = new System.Windows.Forms.TextBox();
((System.ComponentModel.ISupportInitialize)(this.splitContainer1)).BeginInit();
this.splitContainer1.Panel1.SuspendLayout();
this.splitContainer1.Panel2.SuspendLayout();
this.splitContainer1.SuspendLayout();
this.SuspendLayout();
//
// webBrowser1
//
this.webBrowser1.Dock = System.Windows.Forms.DockStyle.Fill;
this.webBrowser1.Location = new System.Drawing.Point(0, 0);
this.webBrowser1.MinimumSize = new System.Drawing.Size(20, 20);
this.webBrowser1.Name = "webBrowser1";
this.webBrowser1.Size = new System.Drawing.Size(527, 309);
this.webBrowser1.TabIndex = 0;
this.webBrowser1.Url = new System.Uri("http://cms.nust.edu.pk/psp/ps/?cmd=login", System.UriKind.Absolute);
//
// splitContainer1
//
this.splitContainer1.Dock = System.Windows.Forms.DockStyle.Fill;
this.splitContainer1.Location = new System.Drawing.Point(0, 0);
this.splitContainer1.Name = "splitContainer1";
this.splitContainer1.Orientation = System.Windows.Forms.Orientation.Horizontal;
//
// splitContainer1.Panel1
//
this.splitContainer1.Panel1.Controls.Add(this.button1);
this.splitContainer1.Panel1.Controls.Add(this.label2);
this.splitContainer1.Panel1.Controls.Add(this.label1);
this.splitContainer1.Panel1.Controls.Add(this.textBox2);
this.splitContainer1.Panel1.Controls.Add(this.textBox1);
//
// splitContainer1.Panel2
//
this.splitContainer1.Panel2.Controls.Add(this.webBrowser1);
this.splitContainer1.Size = new System.Drawing.Size(527, 398);
this.splitContainer1.SplitterDistance = 85;
this.splitContainer1.TabIndex = 1;
//
// button1
//
this.button1.Location = new System.Drawing.Point(330, 31);
this.button1.Name = "button1";
this.button1.Size = new System.Drawing.Size(75, 23);
this.button1.TabIndex = 4;
this.button1.Text = "Insert";
this.button1.UseVisualStyleBackColor = true;
this.button1.Click += new System.EventHandler(this.button1_Click);
//
// label2
//
this.label2.AutoSize = true;
this.label2.Location = new System.Drawing.Point(149, 61);
this.label2.Name = "label2";
this.label2.Size = new System.Drawing.Size(53, 13);
this.label2.TabIndex = 3;
this.label2.Text = "Password";
//
// label1
//
this.label1.AutoSize = true;
this.label1.Location = new System.Drawing.Point(149, 15);
this.label1.Name = "label1";
this.label1.Size = new System.Drawing.Size(55, 13);
this.label1.TabIndex = 2;
this.label1.Text = "Username";
//
// textBox2
//
this.textBox2.Location = new System.Drawing.Point(208, 58);
this.textBox2.Name = "textBox2";
this.textBox2.Size = new System.Drawing.Size(100, 20);
this.textBox2.TabIndex = 1;
//
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(208, 12);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(100, 20);
this.textBox1.TabIndex = 0;
//
// Form1
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(527, 398);
this.Controls.Add(this.splitContainer1);
this.Name = "Form1";
this.Text = "Form1";
this.splitContainer1.Panel1.ResumeLayout(false);
this.splitContainer1.Panel1.PerformLayout();
this.splitContainer1.Panel2.ResumeLayout(false);
((System.ComponentModel.ISupportInitialize)(this.splitContainer1)).EndInit();
this.splitContainer1.ResumeLayout(false);
this.ResumeLayout(false);
}
#endregion
private System.Windows.Forms.WebBrowser webBrowser1;
private System.Windows.Forms.SplitContainer splitContainer1;
private System.Windows.Forms.Button button1;
private System.Windows.Forms.Label label2;
private System.Windows.Forms.Label label1;
private System.Windows.Forms.TextBox textBox2;
private System.Windows.Forms.TextBox textBox1;
}
}