### I need to multiply but I don't know how

 ``1234567891011121314151617181920212223242526`` ``````#include using namespace std; int main () { //declaring variables double Pi= 3.1416 ; double Diameter_ofcircle = 0.0; double priceofrailingmaterial = 0.0; double Totalpriceofrailingmaterial = 0.0; //Getting the user input cout<<"Enter the diameter of the circle "; cin>>Diameter_ofcircle ; cout<<"Enter the price of railing material per foot "; cin>> priceofrailingmaterial ; Totalpriceofrailingmaterial = ( (Diameter_ofcircle)* Pi ) * ( priceofrailingmaterial) ; cout<<"Total price of railing material "<

I need to add this in Visual Studio C++ and this is all I have

 ``123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183`` ``````#pragma once namespace Diameter { 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 for Form1 /// public ref class Form1 : public System::Windows::Forms::Form { public: Form1(void) { InitializeComponent(); // //TODO: Add the constructor code here // } protected: /// /// Clean up any resources being used. /// ~Form1() { if (components) { delete components; } } private: System::Windows::Forms::Label^ label1; private: System::Windows::Forms::TextBox^ txtPi; protected: private: System::Windows::Forms::Label^ label2; private: System::Windows::Forms::TextBox^ txtDiameter; private: System::Windows::Forms::Label^ label3; private: System::Windows::Forms::TextBox^ txtPrice; private: System::Windows::Forms::Label^ label4; private: System::Windows::Forms::TextBox^ txtTotal; private: System::Windows::Forms::Button^ btnClose; private: /// /// Required designer variable. /// System::ComponentModel::Container ^components; #pragma region Windows Form Designer generated code /// /// Required method for Designer support - do not modify /// the contents of this method with the code editor. /// void InitializeComponent(void) { this->label1 = (gcnew System::Windows::Forms::Label()); this->txtPi = (gcnew System::Windows::Forms::TextBox()); this->label2 = (gcnew System::Windows::Forms::Label()); this->txtDiameter = (gcnew System::Windows::Forms::TextBox()); this->label3 = (gcnew System::Windows::Forms::Label()); this->txtPrice = (gcnew System::Windows::Forms::TextBox()); this->label4 = (gcnew System::Windows::Forms::Label()); this->txtTotal = (gcnew System::Windows::Forms::TextBox()); this->btnClose = (gcnew System::Windows::Forms::Button()); this->SuspendLayout(); // // label1 // this->label1->AutoSize = true; this->label1->Location = System::Drawing::Point(12, 90); this->label1->Name = L"label1"; this->label1->Size = System::Drawing::Size(16, 13); this->label1->TabIndex = 0; this->label1->Text = L"Pi"; // // txtPi // this->txtPi->BackColor = System::Drawing::SystemColors::Window; this->txtPi->Location = System::Drawing::Point(124, 87); this->txtPi->Name = L"txtPi"; this->txtPi->ReadOnly = true; this->txtPi->Size = System::Drawing::Size(75, 20); this->txtPi->TabIndex = 1; this->txtPi->Text = L"3.1416"; // // label2 // this->label2->AutoSize = true; this->label2->Location = System::Drawing::Point(12, 32); this->label2->Name = L"label2"; this->label2->Size = System::Drawing::Size(89, 13); this->label2->TabIndex = 2; this->label2->Text = L"Diameter of circle"; // // txtDiameter // this->txtDiameter->Location = System::Drawing::Point(122, 29); this->txtDiameter->Name = L"txtDiameter"; this->txtDiameter->Size = System::Drawing::Size(77, 20); this->txtDiameter->TabIndex = 3; // // label3 // this->label3->AutoSize = true; this->label3->Location = System::Drawing::Point(12, 160); this->label3->Name = L"label3"; this->label3->Size = System::Drawing::Size(154, 13); this->label3->TabIndex = 4; this->label3->Text = L"Price of railing material per foot "; // // txtPrice // this->txtPrice->Location = System::Drawing::Point(194, 215); this->txtPrice->Name = L"txtPrice"; this->txtPrice->Size = System::Drawing::Size(142, 20); this->txtPrice->TabIndex = 5; // // label4 // this->label4->AutoSize = true; this->label4->Location = System::Drawing::Point(12, 215); this->label4->Name = L"label4"; this->label4->Size = System::Drawing::Size(142, 13); this->label4->TabIndex = 6; this->label4->Text = L"Total price of raling material "; // // txtTotal // this->txtTotal->Location = System::Drawing::Point(194, 160); this->txtTotal->Name = L"txtTotal"; this->txtTotal->Size = System::Drawing::Size(122, 20); this->txtTotal->TabIndex = 7; // // btnClose // this->btnClose->Location = System::Drawing::Point(241, 336); this->btnClose->Name = L"btnClose"; this->btnClose->Size = System::Drawing::Size(75, 23); this->btnClose->TabIndex = 8; this->btnClose->Text = L"Close"; this->btnClose->UseVisualStyleBackColor = true; this->btnClose->Click += gcnew System::EventHandler(this, &Form1::btnClose_Click); // // Form1 // this->AutoScaleDimensions = System::Drawing::SizeF(6, 13); this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font; this->ClientSize = System::Drawing::Size(686, 418); this->Controls->Add(this->btnClose); this->Controls->Add(this->txtTotal); this->Controls->Add(this->label4); this->Controls->Add(this->txtPrice); this->Controls->Add(this->label3); this->Controls->Add(this->txtDiameter); this->Controls->Add(this->label2); this->Controls->Add(this->txtPi); this->Controls->Add(this->label1); this->Name = L"Form1"; this->Text = L"Form1"; this->ResumeLayout(false); this->PerformLayout(); } #pragma endregion private: System::Void btnClose_Click(System::Object^ sender, System::EventArgs^ e) { Application::Exit(); } }; } ``````

Looks like you need to add a button, then assign it to do the math.

Don't see the need for you to include the value of PI in your form, I would simply put it in when you click the button.