Visual C++ .NET/GUI Form/ErrorProvider

ErrorProvider Demo

<source lang="csharp"> [STAThreadAttribute] int main(array<System::String ^> ^args) {

 Application::Run(gcnew Form1());
 return 0;

}

 using namespace System;
 using namespace System::ComponentModel;
 using namespace System::Collections;
 using namespace System::Windows::Forms;
 using namespace System::Data;
 using namespace System::Drawing;
 public ref class Form1 : public System::Windows::Forms::Form
 {
 public:
   Form1(void)
   {
     InitializeComponent();
   }
 private:
       System::Windows::Forms::TextBox^  tbPword;
       System::Windows::Forms::Label^  lbPword;
       System::Windows::Forms::Button^  bnLogin;
       System::Windows::Forms::TextBox^  tbName;
       System::Windows::Forms::Label^  lbName;
       System::Windows::Forms::ErrorProvider^  eProvider;
   void InitializeComponent(void)
   {
           this->tbPword = (gcnew System::Windows::Forms::TextBox());
           this->lbPword = (gcnew System::Windows::Forms::Label());
           this->bnLogin = (gcnew System::Windows::Forms::Button());
           this->tbName = (gcnew System::Windows::Forms::TextBox());
           this->lbName = (gcnew System::Windows::Forms::Label());
           this->eProvider =(gcnew System::Windows::Forms::ErrorProvider());
           (cli::safe_cast<System::ComponentModel::ISupportInitialize^>
               (this->eProvider))->BeginInit();
           this->SuspendLayout();
           //
           // tbPword
           //
           this->tbPword->Location = System::Drawing::Point(103, 83);
           this->tbPword->Name = L"tbPword";
           this->tbPword->PasswordChar = "*";
           this->tbPword->Size = System::Drawing::Size(100, 20);
           this->tbPword->TabIndex = 9;
           this->tbPword->Validating +=
               gcnew System::ComponentModel::CancelEventHandler(this,
                                                  &Form1::textbox_Validating);
           //
           // lbPword
           //
           this->lbPword->AutoSize = true;
           this->lbPword->Location = System::Drawing::Point(34, 83);
           this->lbPword->Name = L"lbPword";
           this->lbPword->Size = System::Drawing::Size(53, 13);
           this->lbPword->TabIndex = 8;
           this->lbPword->Text = L"&Password";
           //
           // bnLogin
           //
           this->bnLogin->Location = System::Drawing::Point(75, 131);
           this->bnLogin->Name = L"bnLogin";
           this->bnLogin->Size = System::Drawing::Size(75, 23);
           this->bnLogin->TabIndex = 7;
           this->bnLogin->Text = L"&Login";
           this->bnLogin->Click +=
               gcnew System::EventHandler(this, &Form1::login_Click);
           //
           // tbName
           //
           this->tbName->Location = System::Drawing::Point(103, 31);
           this->tbName->Name = L"tbName";
           this->tbName->Size = System::Drawing::Size(100, 20);
           this->tbName->TabIndex = 6;
           this->tbName->Validating +=
               gcnew System::ComponentModel::CancelEventHandler(this,
                                                  &Form1::textbox_Validating);
           //
           // lbName
           //
           this->lbName->AutoSize = true;
           this->lbName->Location = System::Drawing::Point(34, 31);
           this->lbName->Name = L"lbName";
           this->lbName->Size = System::Drawing::Size(35, 13);
           this->lbName->TabIndex = 5;
           this->lbName->Text = L"&Name";
           //
           // eProvider
           //
           this->eProvider->ContainerControl = this;
           //
           // Form1
           //
           this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
           this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
           this->ClientSize = System::Drawing::Size(237, 185);
           this->Controls->Add(this->tbPword);
           this->Controls->Add(this->lbPword);
           this->Controls->Add(this->bnLogin);
           this->Controls->Add(this->tbName);
           this->Controls->Add(this->lbName);
           this->Name = L"Form1";
           this->Text = L"System Login";
           (cli::safe_cast<System::ComponentModel::ISupportInitialize^>
               (this->eProvider))->EndInit();
           this->ResumeLayout(false);
           this->PerformLayout();
   }
       System::Void textbox_Validating(System::Object^ sender,
                                   System::ComponentModel::CancelEventArgs^ e)
       {
           try
           {
               TextBox ^tb = (TextBox^)(sender);
               if (tb->Text->Equals(""))
                   eProvider->SetError(tb, "**Error** Missing Entry!");
               else
                   eProvider->SetError(tb, "");
           }
           catch (Exception^)
           {
               // Not TextBox
           }
       }
       System::Void login_Click(System::Object^ sender, System::EventArgs^ e)
       {
           if (tbName->Text->Equals(""))
               eProvider->SetError(tbName, "**Error** Missing Entry!");
           else
               eProvider->SetError(tbName, "");

           if (tbPword->Text->Equals(""))
           {
               // Place the icon left side of control
               eProvider->SetIconAlignment(tbPword,
                                           ErrorIconAlignment::MiddleLeft);
               eProvider->SetError(tbPword, "**Error** Missing Entry!");
           }
           else
               eProvider->SetError(tbPword, "");
       }
 };

}

 </source>