求助 正则表达式获取网页编码（gb2312）失败

#pragma once


namespace GetWebpageCode {

    using namespace System;
    using namespace System::ComponentModel;
    using namespace System::Collections;
    using namespace System::Windows::Forms;
    using namespace System::Data;
    using namespace System::Drawing;
    using namespace System::Net;
    using namespace System::Text;
    using namespace System::Text::RegularExpressions;

    /// <summary>
    /// Form1 摘要
    /// </summary>
    public ref class Form1 : public System::Windows::Forms::Form
    {
    public:
        Form1(void)
        {
            InitializeComponent();
            //
            //TODO:  在此处添加构造函数代码
            //
        }

    protected:
        /// <summary>
        /// 清理所有正在使用的资源。
        /// </summary>
        ~Form1()
        {
            if (components)
            {
                delete components;
            }
        }
    private: System::Windows::Forms::Button^ button1;
    protected:
    private: System::Windows::Forms::Button^ button2;
    private: System::Windows::Forms::Button^ button3;
    private: System::Windows::Forms::Button^ button4;
    private: System::Windows::Forms::Button^ button5;
    private: System::Windows::Forms::Button^ button6;
    private: System::Windows::Forms::TextBox^ textBox1;
    private: System::Windows::Forms::TextBox^ textBox2;

    private:
        /// <summary>
        /// 必需的设计器变量。
        /// </summary>
        System::ComponentModel::Container ^components;

#pragma region Windows Form Designer generated code
        /// <summary>
        /// 设计器支持所需的方法 - 不要修改
        /// 使用代码编辑器修改此方法的内容。
        /// </summary>
        void InitializeComponent(void)
        {
            this->button1 = (gcnew System::Windows::Forms::Button());
            this->button2 = (gcnew System::Windows::Forms::Button());
            this->button3 = (gcnew System::Windows::Forms::Button());
            this->button4 = (gcnew System::Windows::Forms::Button());
            this->button5 = (gcnew System::Windows::Forms::Button());
            this->button6 = (gcnew System::Windows::Forms::Button());
            this->textBox1 = (gcnew System::Windows::Forms::TextBox());
            this->textBox2 = (gcnew System::Windows::Forms::TextBox());
            this->SuspendLayout();
            //
            // button1
            //
            this->button1->Font = (gcnew System::Drawing::Font(L"宋体", 12));
            this->button1->Location = System::Drawing::Point(33, 53);
            this->button1->Name = L"button1";
            this->button1->Size = System::Drawing::Size(100, 35);
            this->button1->TabIndex = 0;
            this->button1->Text = L"button1";
            this->button1->UseVisualStyleBackColor = true;
            this->button1->Click += gcnew System::EventHandler(this, &Form1::button1_Click);
            //
            // button2
            //
            this->button2->Font = (gcnew System::Drawing::Font(L"宋体", 12));
            this->button2->Location = System::Drawing::Point(196, 53);
            this->button2->Name = L"button2";
            this->button2->Size = System::Drawing::Size(100, 35);
            this->button2->TabIndex = 1;
            this->button2->Text = L"button2";
            this->button2->UseVisualStyleBackColor = true;
            //
            // button3
            //
            this->button3->Font = (gcnew System::Drawing::Font(L"宋体", 12));
            this->button3->Location = System::Drawing::Point(359, 53);
            this->button3->Name = L"button3";
            this->button3->Size = System::Drawing::Size(100, 35);
            this->button3->TabIndex = 2;
            this->button3->Text = L"button3";
            this->button3->UseVisualStyleBackColor = true;
            //
            // button4
            //
            this->button4->Font = (gcnew System::Drawing::Font(L"宋体", 12));
            this->button4->Location = System::Drawing::Point(522, 53);
            this->button4->Name = L"button4";
            this->button4->Size = System::Drawing::Size(100, 35);
            this->button4->TabIndex = 3;
            this->button4->Text = L"button4";
            this->button4->UseVisualStyleBackColor = true;
            //
            // button5
            //
            this->button5->Font = (gcnew System::Drawing::Font(L"宋体", 12));
            this->button5->Location = System::Drawing::Point(685, 53);
            this->button5->Name = L"button5";
            this->button5->Size = System::Drawing::Size(100, 35);
            this->button5->TabIndex = 4;
            this->button5->Text = L"button5";
            this->button5->UseVisualStyleBackColor = true;
            //
            // button6
            //
            this->button6->Font = (gcnew System::Drawing::Font(L"宋体", 12));
            this->button6->Location = System::Drawing::Point(848, 53);
            this->button6->Name = L"button6";
            this->button6->Size = System::Drawing::Size(100, 35);
            this->button6->TabIndex = 5;
            this->button6->Text = L"button6";
            this->button6->UseVisualStyleBackColor = true;
            //
            // textBox1
            //
            this->textBox1->Font = (gcnew System::Drawing::Font(L"宋体", 12));
            this->textBox1->Location = System::Drawing::Point(32, 12);
            this->textBox1->Name = L"textBox1";
            this->textBox1->Size = System::Drawing::Size(915, 26);
            this->textBox1->TabIndex = 6;
            //
            // textBox2
            //
            this->textBox2->Location = System::Drawing::Point(0, 104);
            this->textBox2->Multiline = true;
            this->textBox2->Name = L"textBox2";
            this->textBox2->ScrollBars = System::Windows::Forms::ScrollBars::Vertical;
            this->textBox2->Size = System::Drawing::Size(1007, 536);
            this->textBox2->TabIndex = 7;
            //
            // Form1
            //
            this->AutoScaleDimensions = System::Drawing::SizeF(6, 12);
            this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
            this->ClientSize = System::Drawing::Size(1008, 641);
            this->Controls->Add(this->textBox2);
            this->Controls->Add(this->textBox1);
            this->Controls->Add(this->button6);
            this->Controls->Add(this->button5);
            this->Controls->Add(this->button4);
            this->Controls->Add(this->button3);
            this->Controls->Add(this->button2);
            this->Controls->Add(this->button1);
            this->Name = L"Form1";
            this->Text = L"Form1";
            this->ResumeLayout(false);
            this->PerformLayout();

        }
#pragma endregion
    private:String^ WebPageCode;
    private:System::Void button1_Click(System::Object^ sender, System::EventArgs^ e)
    {
        WebClient^ myWebClient = gcnew WebClient;

        array<Byte>^ mybuffer = myWebClient->DownloadData(textBox1->Text);
        //WebPageCode = Encoding::GetEncoding(936)->GetString(mybuffer);
        //UTF8Encoding temp;
        ASCIIEncoding temp;
        WebPageCode=temp.GetString(mybuffer);
        Regex^ charcode=gcnew Regex(".*?charset[=](.*?)[\"] > .*");
        String^ StrCode = charcode->Replace(WebPageCode, "$1");
        WebPageCode = Encoding::GetEncoding(StrCode)->GetString(mybuffer);
        textBox2->Text = WebPageCode;
    }
};
}