Ошибка при написании калькулятора: нарушение прав доступа при записи по адресу

#include "MyForm.h"
 
using namespace System;
using namespace System::Windows::Forms;
[STAThreadAttribute]
void Main(array<String^>^ args) {
    Application::EnableVisualStyles();
    Application::SetCompatibleTextRenderingDefault(false);
    Project10::MyForm form;
    Application::Run(% form);

#pragma once
#include <math.h>
 
namespace Project10 {
 
    using namespace System;
    using namespace System::ComponentModel;
    using namespace System::Collections;
    using namespace System::Windows::Forms;
    using namespace System::Data;
    using namespace System::Drawing;
 
    /// <summary>
    /// Сводка для MyForm
    /// </summary>
    public ref class MyForm : public System::Windows::Forms::Form
    {
    public:
        MyForm(void)
        {
            InitializeComponent();
            //
            //TODO: добавьте код конструктора
            //
        }
 
    protected:
        /// <summary>
        /// Освободить все используемые ресурсы.
        /// </summary>
        ~MyForm()
        {
            if (components)
            {
                delete components;
            }
        }
    private: System::Windows::Forms::TextBox^ textBox1;
    protected:
    private: System::Windows::Forms::Button^ button_Delete;
    private: System::Windows::Forms::Button^ button_DeleteAll;
    private: System::Windows::Forms::Button^ button_Kvadrat;
    private: System::Windows::Forms::Button^ button_Plus;
    private: System::Windows::Forms::Button^ button_Koren;
    private: System::Windows::Forms::Button^ button_Minus;
    private: System::Windows::Forms::Button^ button9;
    private: System::Windows::Forms::Button^ button8;
    private: System::Windows::Forms::Button^ button7;
    private: System::Windows::Forms::Button^ button_Delenie;
    private: System::Windows::Forms::Button^ button6;
    private: System::Windows::Forms::Button^ button5;
    private: System::Windows::Forms::Button^ button4;
    private: System::Windows::Forms::Button^ button_Umnojenie;
    private: System::Windows::Forms::Button^ hj;
    private: System::Windows::Forms::Button^ fd;
    private: System::Windows::Forms::Button^ vbc;
    private: System::Windows::Forms::Button^ button_Ravno;
    private: System::Windows::Forms::Button^ button_Tochka;
    private: System::Windows::Forms::Button^ button0;
    private: System::Windows::Forms::Button^ button_PlusOrMinus;
    private: System::Windows::Forms::Label^ lbl;
 
 
    private:
        /// <summary>
        /// Обязательная переменная конструктора.
        /// </summary>
        System::ComponentModel::Container ^components;
 
#pragma region Windows Form Designer generated code
        /// <summary>
        /// Требуемый метод для поддержки конструктора — не изменяйте 
        /// содержимое этого метода с помощью редактора кода.
        /// </summary>
        void InitializeComponent(void)
        {
            this->textBox1 = (gcnew System::Windows::Forms::TextBox());
            this->button_Delete = (gcnew System::Windows::Forms::Button());
            this->button_DeleteAll = (gcnew System::Windows::Forms::Button());
            this->button_Kvadrat = (gcnew System::Windows::Forms::Button());
            this->button_Plus = (gcnew System::Windows::Forms::Button());
            this->button_Koren = (gcnew System::Windows::Forms::Button());
            this->button_Minus = (gcnew System::Windows::Forms::Button());
            this->button9 = (gcnew System::Windows::Forms::Button());
            this->button8 = (gcnew System::Windows::Forms::Button());
            this->button7 = (gcnew System::Windows::Forms::Button());
            this->button_Delenie = (gcnew System::Windows::Forms::Button());
            this->button6 = (gcnew System::Windows::Forms::Button());
            this->button5 = (gcnew System::Windows::Forms::Button());
            this->button4 = (gcnew System::Windows::Forms::Button());
            this->button_Umnojenie = (gcnew System::Windows::Forms::Button());
            this->hj = (gcnew System::Windows::Forms::Button());
            this->fd = (gcnew System::Windows::Forms::Button());
            this->vbc = (gcnew System::Windows::Forms::Button());
            this->button_Ravno = (gcnew System::Windows::Forms::Button());
            this->button_Tochka = (gcnew System::Windows::Forms::Button());
            this->button0 = (gcnew System::Windows::Forms::Button());
            this->button_PlusOrMinus = (gcnew System::Windows::Forms::Button());
            this->lbl = (gcnew System::Windows::Forms::Label());
            this->SuspendLayout();
            // 
            // textBox1
            // 
            this->textBox1->Location = System::Drawing::Point(18, 20);
            this->textBox1->Multiline = true;
            this->textBox1->Name = L"textBox1";
            this->textBox1->Size = System::Drawing::Size(249, 62);
            this->textBox1->TabIndex = 0;
            this->textBox1->TextAlign = System::Windows::Forms::HorizontalAlignment::Right;
            // 
            // button_Delete
            // 
            this->button_Delete->Location = System::Drawing::Point(290, 20);
            this->button_Delete->Name = L"button_Delete";
            this->button_Delete->Size = System::Drawing::Size(68, 58);
            this->button_Delete->TabIndex = 1;
            this->button_Delete->Text = L"<==";
            this->button_Delete->UseVisualStyleBackColor = true;
            // 
            // button_DeleteAll
            // 
            this->button_DeleteAll->Location = System::Drawing::Point(22, 106);
            this->button_DeleteAll->Name = L"button_DeleteAll";
            this->button_DeleteAll->Size = System::Drawing::Size(67, 66);
            this->button_DeleteAll->TabIndex = 2;
            this->button_DeleteAll->Text = L"C";
            this->button_DeleteAll->UseVisualStyleBackColor = true;
            // 
            // button_Kvadrat
            // 
            this->button_Kvadrat->Location = System::Drawing::Point(112, 106);
            this->button_Kvadrat->Name = L"button_Kvadrat";
            this->button_Kvadrat->Size = System::Drawing::Size(67, 66);
            this->button_Kvadrat->TabIndex = 3;
            this->button_Kvadrat->Text = L"^";
            this->button_Kvadrat->UseVisualStyleBackColor = true;
            // 
            // button_Plus
            // 
            this->button_Plus->Location = System::Drawing::Point(290, 106);
            this->button_Plus->Name = L"button_Plus";
            this->button_Plus->Size = System::Drawing::Size(67, 66);
            this->button_Plus->TabIndex = 5;
            this->button_Plus->Text = L"+";
            this->button_Plus->UseVisualStyleBackColor = true;
            // 
            // button_Koren
            // 
            this->button_Koren->Location = System::Drawing::Point(200, 106);
            this->button_Koren->Name = L"button_Koren";
            this->button_Koren->Size = System::Drawing::Size(67, 66);
            this->button_Koren->TabIndex = 4;
            this->button_Koren->Text = L"/^";
            this->button_Koren->UseVisualStyleBackColor = true;
            // 
            // button_Minus
            // 
            this->button_Minus->Location = System::Drawing::Point(290, 197);
            this->button_Minus->Name = L"button_Minus";
            this->button_Minus->Size = System::Drawing::Size(67, 66);
            this->button_Minus->TabIndex = 9;
            this->button_Minus->Text = L"-";
            this->button_Minus->UseVisualStyleBackColor = true;
            // 
            // button9
            // 
            this->button9->Location = System::Drawing::Point(200, 197);
            this->button9->Name = L"button9";
            this->button9->Size = System::Drawing::Size(67, 66);
            this->button9->TabIndex = 8;
            this->button9->Text = L"9";
            this->button9->UseVisualStyleBackColor = true;
            // 
            // button8
            // 
            this->button8->Location = System::Drawing::Point(112, 197);
            this->button8->Name = L"button8";
            this->button8->Size = System::Drawing::Size(67, 66);
            this->button8->TabIndex = 7;
            this->button8->Text = L"8";
            this->button8->UseVisualStyleBackColor = true;
            // 
            // button7
            // 
            this->button7->Location = System::Drawing::Point(22, 197);
            this->button7->Name = L"button7";
            this->button7->Size = System::Drawing::Size(67, 66);
            this->button7->TabIndex = 6;
            this->button7->Text = L"7";
            this->button7->UseVisualStyleBackColor = true;
            // 
            // button_Delenie
            // 
            this->button_Delenie->Location = System::Drawing::Point(290, 288);
            this->button_Delenie->Name = L"button_Delenie";
            this->button_Delenie->Size = System::Drawing::Size(67, 66);
            this->button_Delenie->TabIndex = 13;
            this->button_Delenie->Text = L"/";
            this->button_Delenie->UseVisualStyleBackColor = true;
            // 
            // button6
            // 
            this->button6->Location = System::Drawing::Point(200, 288);
            this->button6->Name = L"button6";
            this->button6->Size = System::Drawing::Size(67, 66);
            this->button6->TabIndex = 12;
            this->button6->Text = L"6";
            this->button6->UseVisualStyleBackColor = true;
            // 
            // button5
            // 
            this->button5->Location = System::Drawing::Point(112, 288);
            this->button5->Name = L"button5";
            this->button5->Size = System::Drawing::Size(67, 66);
            this->button5->TabIndex = 11;
            this->button5->Text = L"5";
            this->button5->UseVisualStyleBackColor = true;
            // 
            // button4
            // 
            this->button4->Location = System::Drawing::Point(22, 288);
            this->button4->Name = L"button4";
            this->button4->Size = System::Drawing::Size(67, 66);
            this->button4->TabIndex = 10;
            this->button4->Text = L"4";
            this->button4->UseVisualStyleBackColor = true;
            // 
            // button_Umnojenie
            // 
            this->button_Umnojenie->Location = System::Drawing::Point(290, 384);
            this->button_Umnojenie->Name = L"button_Umnojenie";
            this->button_Umnojenie->Size = System::Drawing::Size(67, 66);
            this->button_Umnojenie->TabIndex = 17;
            this->button_Umnojenie->Text = L"*";
            this->button_Umnojenie->UseVisualStyleBackColor = true;
            // 
            // hj
            // 
            this->hj->Location = System::Drawing::Point(200, 384);
            this->hj->Name = L"hj";
            this->hj->Size = System::Drawing::Size(67, 66);
            this->hj->TabIndex = 16;
            this->hj->Text = L"3";
            this->hj->UseVisualStyleBackColor = true;
            // 
            // fd
            // 
            this->fd->Location = System::Drawing::Point(112, 384);
            this->fd->Name = L"fd";
            this->fd->Size = System::Drawing::Size(67, 66);
            this->fd->TabIndex = 15;
            this->fd->Text = L"2";
            this->fd->UseVisualStyleBackColor = true;
            // 
            // vbc
            // 
            this->vbc->Location = System::Drawing::Point(22, 384);
            this->vbc->Name = L"vbc";
            this->vbc->Size = System::Drawing::Size(67, 66);
            this->vbc->TabIndex = 14;
            this->vbc->Text = L"1";
            this->vbc->UseVisualStyleBackColor = true;
            // 
            // button_Ravno
            // 
            this->button_Ravno->Location = System::Drawing::Point(290, 468);
            this->button_Ravno->Name = L"button_Ravno";
            this->button_Ravno->Size = System::Drawing::Size(67, 66);
            this->button_Ravno->TabIndex = 21;
            this->button_Ravno->Text = L"=";
            this->button_Ravno->UseVisualStyleBackColor = true;
            // 
            // button_Tochka
            // 
            this->button_Tochka->Location = System::Drawing::Point(200, 468);
            this->button_Tochka->Name = L"button_Tochka";
            this->button_Tochka->Size = System::Drawing::Size(67, 66);
            this->button_Tochka->TabIndex = 20;
            this->button_Tochka->Text = L".";
            this->button_Tochka->UseVisualStyleBackColor = true;
            // 
            // button0
            // 
            this->button0->Location = System::Drawing::Point(112, 468);
            this->button0->Name = L"button0";
            this->button0->Size = System::Drawing::Size(67, 66);
            this->button0->TabIndex = 19;
            this->button0->Text = L"0";
            this->button0->UseVisualStyleBackColor = true;
            // 
            // button_PlusOrMinus
            // 
            this->button_PlusOrMinus->Location = System::Drawing::Point(22, 468);
            this->button_PlusOrMinus->Name = L"button_PlusOrMinus";
            this->button_PlusOrMinus->Size = System::Drawing::Size(67, 66);
            this->button_PlusOrMinus->TabIndex = 18;
            this->button_PlusOrMinus->Text = L"+/-";
            this->button_PlusOrMinus->UseVisualStyleBackColor = true;
            // 
            // lbl
            // 
            this->lbl->AutoSize = true;
            this->lbl->Location = System::Drawing::Point(22, 29);
            this->lbl->Name = L"lbl";
            this->lbl->Size = System::Drawing::Size(0, 20);
            this->lbl->TabIndex = 22;
            // 
            // MyForm
            // 
            this->AutoScaleDimensions = System::Drawing::SizeF(9, 20);
            this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
            this->ClientSize = System::Drawing::Size(379, 561);
            this->Controls->Add(this->lbl);
            this->Controls->Add(this->button_Ravno);
            this->Controls->Add(this->button_Tochka);
            this->Controls->Add(this->button0);
            this->Controls->Add(this->button_PlusOrMinus);
            this->Controls->Add(this->button_Umnojenie);
            this->Controls->Add(this->hj);
            this->Controls->Add(this->fd);
            this->Controls->Add(this->vbc);
            this->Controls->Add(this->button_Delenie);
            this->Controls->Add(this->button6);
            this->Controls->Add(this->button5);
            this->Controls->Add(this->button4);
            this->Controls->Add(this->button_Minus);
            this->Controls->Add(this->button9);
            this->Controls->Add(this->button8);
            this->Controls->Add(this->button7);
            this->Controls->Add(this->button_Plus);
            this->Controls->Add(this->button_Koren);
            this->Controls->Add(this->button_Kvadrat);
            this->Controls->Add(this->button_DeleteAll);
            this->Controls->Add(this->button_Delete);
            this->Controls->Add(this->textBox1);
            this->Name = L"MyForm";
            this->Text = L"MyForm";
            this->ResumeLayout(false);
            this->PerformLayout();
 
        }
#pragma endregion
        double iFirstnum;
        double iSecondnum;
        double iResolt;
        String^ iOperate;
 
        //Знак равно
private: System::Void button12_Click(System::Object^ sender, System::EventArgs^ e) {
    lbl->Text = "";
    iSecondnum = Double::Parse(textBox1->Text);
    if (iOperate == "+") {
        iResolt = iFirstnum + iSecondnum;
        textBox1->Text = System::Convert::ToString(iResolt);
    }
    else if (iOperate == "-") {
        iResolt = iFirstnum - iSecondnum;
        textBox1->Text = System::Convert::ToString(iResolt);
 
    }
    else if (iOperate == "/") {
        iResolt = iFirstnum / iSecondnum;
        textBox1->Text = System::Convert::ToString(iResolt);
    }
    else
        if (iOperate == "x") {
            iResolt = iFirstnum * iSecondnum;
            textBox1->Text = System::Convert::ToString(iResolt);
        }
        else if (iOperate == "^") {
            iResolt = pow(iFirstnum, iSecondnum);
            textBox1->Text = System::Convert::ToString(iResolt);
        }
 
 
}
private: System::Void button18_Click(System::Object^ sender, System::EventArgs^ e) {
    if (textBox1->Text->Contains("-")) {
        textBox1->Text = textBox1->Text->Remove(0, 1);
    }
    else
    {
        textBox1->Text = "-" + textBox1->Text;
 
    }
}
private: System::Void MyForm_Load(System::Object^ sender, System::EventArgs^ e) {
}
private: System::Void label1_Click(System::Object^ sender, System::EventArgs^ e) {
}
 
 
private: System::Void textBox1_TextChanged(System::Object^ sender, System::EventArgs^ e) {
    if (textBox1->Text == "") {
        textBox1->Text = "0";
    }
}
private: System::Void button_DeleteAll_Click(System::Object^ sender, System::EventArgs^ e) {
    textBox1->Text = "0";
    lbl->Text = "";
 
}
 
 
private: System::Void buton_click(System::Object^ sender, System::EventArgs^ e) {
    Button^ Numbers = safe_cast <Button^>(sender);
    if (textBox1->Text == "0")
    {
        textBox1->Text = Numbers->Text;
    }
    else
    {
        textBox1->Text = textBox1->Text + Numbers->Text;
    }
 
}
 
private: System::Void Arithmetic(System::Object^ sender, System::EventArgs^ e) {
    Button^ op = safe_cast <Button^>(sender);
    iFirstnum = double::Parse(textBox1->Text);
    textBox1->Text = "";
    iOperate = op->Text;
    lbl->Text = System::Convert::ToString(iFirstnum) + "" + iOperate;
    if (iOperate == "/^") {
        iResolt = sqrt(iFirstnum);
        textBox1->Text = System::Convert::ToString(iResolt);
    }
 
 
}
 
private: System::Void button_Delete_Click(System::Object^ sender, System::EventArgs^ e) {
    if (textBox1->Text->Length > 0) {
        textBox1->Text = textBox1->Text->Remove(textBox1->Text->Length - 1, 1);
    }
}
private: System::Void button_Tochka_Click(System::Object^ sender, System::EventArgs^ e) {
    if (!textBox1->Text->Contains(",")) {
        textBox1->Text = textBox1->Text + ",";
    }
 
}
private: System::Void label1_Click_1(System::Object^ sender, System::EventArgs^ e) {
}
};
}