Changing the value of a control property through codes (Windows Forms Application-Microsoft Visual C++ 2008 Express Edition)

In case you might not notice, Visual Programming otherwise known as Object-Oriented programming revolves around changing the values of a property of an object through codes. To change the value of a control property using codes in Visual C++ Express Edition, use the following syntax:

//enclosed the value in a quotation mark 
//if the value of a property is a string
this->ControlName->Property=”value”; 
//do not add quotation marks
//if the value of the property is Boolean or Number
this->ControlName->Property=value;

The following steps illustrate a sample application of this syntax:

1. Start MSVC++ Express 2008 by clicking on the Start button, All Programs then clicking on the Microsoft Visual C++ Express Edition Start menu option.

2. Click File>New>Project. The new project dialog box will then come into view.

3. Select Windows Forms Application from the Visual Studio Installed templates, type the project name>Click Ok.
After clicking the Ok button, an IDE suited for windows forms application will then appear containing a form, a toolbox window, and a properties window.

4. Design your interface similar to the one shown below:



Note: Those texts that appear beside each control are the suggested names for our form controls in this example. If you notice I am using .Net naming convention in naming controls because it is simpler to use than Leszynski naming convention. To change the value of the name property of each control, just click each individual control then locate the name property in the properties window then assign those descriptive names in our illustration correspondingly.


5. Double-click the control named FnameButton, then enter:

//this will assign John as an FnameLabel text
this->FnameLabel->Text=”John”; 

Your code will now look like this:

private: System::Void FnameButton_Click(System::Object^  sender, System::EventArgs^  e) {
this->FnameLabel->Text=”John”;
}

6. Double-click LnameButton, the following should then the following between the open and close curly brackets:

//this will assign John as an FnameLabel text
this->LnameLabel->Text=”Doe”; 

Your code will now look like this:

private: System::Void LnameButton_Click(System::Object^  sender, System::EventArgs^  e) {
this->LnameLabel->Text=”Doe”;
}

7. Double-click the control named ExitButton, then type this->Close(); between the open and curly brackets. The Close() method terminates the current form.

Your code will now look like this::

private: System::Void ExitButton_Click(System::Object^  sender, System::EventArgs^  e) {
this->Close();
}

8. Press F5 to run your application. If all went well, you will see our sample application instantly without build erros.

Using Math Operators (Windows Forms Applications-Microsoft Visual C++ 2008 Express Edition)

As you may already know, math operators are used to perform mathematical computations and just like any other languages, MSVC++ 2008 Express supports the following basic math operators:

(+)Addition
(-)Subtraction
(/)Division
(*)Multiplication

The following steps demonstrate these operators at work:

1. Start MSVC++ Express 2008 by clicking on the Start button, All Programs then clicking on the Microsoft Visual C++ Express Edition Start menu option.

2. Click File>New>Project. The new project dialog box will then come into view.

3. Select Windows Forms Application from the Visual Studio Installed templates, type the project name>Click Ok.
After clicking the Ok button, an IDE suited for windows forms application will then appear containing a form, a toolbox window, and a properties window.

4. Create a user interface similar to the one below:



Note: Those texts that appear beside each control are the suggested names for our form controls in this example. If you noticed I am using .Net naming convention in naming controls because it is simpler to use than Leszynski naming convention. To change the value of the name property of each control, just click each individual control then locate the name property in the properties window then assign those descriptive names in our illustration correspondingly.

5. Double-click your form then locate the following line:

#pragma endregion

6. Declare the following variables below it:

int intnum1, intnum2, intans;

Declaring these variables below the #pragma endregion line allows our variables to be available publicly and to be used by other procedures.

Your code should now appear just like this:

#pragma endregion
int intnum1, intnum2,intans;

7. Double-click the control named TimesButton,type the following:

intnum1=int::Parse(this->FnumTextBox->Text);
intnum2=int::Parse(this->SnumTextBox->Text);
intans=intnum1 * intnum2;
this->OperatorLabel->Text="*";
this->AnsLabel->Text=Convert::ToString(intans);

Your code should now appear just like this:

private: System::Void TimesButton_Click(System::Object^  sender, System::EventArgs^  e) {
intnum1=int::Parse(this->FnumTextBox->Text);
intnum2=int::Parse(this->SnumTextBox->Text);
intans=intnum1 * intnum2;
this->OperatorLabel->Text="*";
this->AnsLabel->Text=Convert::ToString(intans);
}

8. Double-click the control named DivButton,type the following:

intnum1=int::Parse(this->FnumTextBox->Text);
intnum2=int::Parse(this->SnumTextBox->Text);
intans=intnum1 / intnum2;
this->OperatorLabel->Text="/";
this->AnsLabel->Text=Convert::ToString(intans);

Your code should now appear just like this:

private: System::Void DivButton_Click(System::Object^  sender, System::EventArgs^  e) {
intnum1=int::Parse(this->FnumTextBox->Text);
intnum2=int::Parse(this->SnumTextBox->Text);
intans=intnum1 / intnum2;
this->OperatorLabel->Text="/";
this->AnsLabel->Text=Convert::ToString(intans);
}

9. Double-click the control named AddButton,type the following:

intnum1=int::Parse(this->FnumTextBox->Text);
intnum2=int::Parse(this->SnumTextBox->Text);
intans=intnum1 + intnum2;
this->OperatorLabel->Text="+";
this->AnsLabel->Text=Convert::ToString(intans);

Your code should now appear just like this:

private: System::Void AddButton_Click(System::Object^  sender, System::EventArgs^  e) {
intnum1=int::Parse(this->FnumTextBox->Text);
intnum2=int::Parse(this->SnumTextBox->Text);
intans=intnum1 + intnum2;
this->OperatorLabel->Text="+";
this->AnsLabel->Text=Convert::ToString(intans);
}

10. Double-click the control named DiffButton,type the following:

intnum1=int::Parse(this->FnumTextBox->Text);
intnum2=int::Parse(this->SnumTextBox->Text);
intans=intnum1 - intnum2;
this->OperatorLabel->Text="-";
this->AnsLabel->Text=Convert::ToString(intans);

Your code should now appear just like this:

private: System::Void DiffButton_Click(System::Object^  sender, System::EventArgs^  e) {
intnum1=int::Parse(this->FnumTextBox->Text);
intnum2=int::Parse(this->SnumTextBox->Text);
intans=intnum1 - intnum2;
this->OperatorLabel->Text="-";
this->AnsLabel->Text=Convert::ToString(intans);
}

11. Double-click the control named ClearButton,type the following:

this->FnumTextBox->Text="";
this->SnumTextBox->Text="";
this->OperatorLabel->Text="";
this->AnsLabel->Text="";

Your code will now look like this:

private: System::Void ClearButton_Click(System::Object^  sender, System::EventArgs^  e) {
this->FnumTextBox->Text="";
this->SnumTextBox->Text="";
this->OperatorLabel->Text="";
this->AnsLabel->Text="";
}

12.Double-click ExitButton, then type this->Close:

private: System::Void ExitButton_Click(System::Object^  sender, System::EventArgs^  e) {
this->Close();
}

13. Press F5 to execute your application. I will add comments to the codes above when I have time. Till then:)