Microsoft Visual C# Example Application: Percentage Conversions

 Introduction
 In mathematics and related subjects such as algebra or statistics, a percentage is used to express a value that is a fraction between 0 and 1. It is sometimes expressed as x%.
 There are various scenarios for which you deal with percent values: Sometimes you get a decimal value that is between 0 and 1, such as 0.86 or 0.1245, and you need its percentage equivalent Sometimes you are given a fraction, such as 3/8 and must know how must that value represents in percent Sometimes you have a percent value but must convert it to decimal
 Application: Creating the Application
1. Start Microsoft Visual Studio
2. To create a new application, on the main menu, click File -> New Project...
3. In the middle list, click Windows Forms Application
4. Change the Name to PercentageConversions
5. Click OK
6. Design the form as follows:

 Control Text Name TextAlign GroupBox Converting a Percentage to Decimal Label Value: TextBox 5 txtPercentage1 Right Label % of TextBox 10 txtValue1 Right Button = btnConvert1 TextBox txtValue1 Right GroupBox Converting a Fraction to a Percentage TextBox 3 txtNumerator Right Label / TextBox 4 txtDenominator Right Button = btnFractionToPercent TextBox txtPercentage2 Right Label % GroupBox Converting a Decimal to Percentage Label Value: TextBox 0.125 txtDecimal1 Right Button = btnDecimalToPercent TextBox txtPercentage3 Right Label % GroupBox Converting a Percentage to Decimal Label Value: TextBox 75 txtPercentage4 Right Label % Button = btnPercentToDecimal TextBox txtDecimal2 Right Button Close btnClose
7. Double-click the first = button
8. Implement its event as follows:
```private void btnConvert1_Click_1(object sender, EventArgs e)
{
double percent = 0.00;
double value = 0.00;
double result;

try
{
percent = double.Parse(txtPercentage1.Text);
}
catch (FormatException)
{
MessageBox.Show("Invalid Percent Value", "Percentage Conversion");
}

try
{
value = double.Parse(txtValue1.Text);
}
catch (FormatException)
{
MessageBox.Show("Invalid Value to Convert", "Percentage Conversion");
}

result = percent * value / 100;
txtResult1.Text = result.ToString("F");
}```
10. Double-click the second = button
11. Implement its event as follows:
```private void btnFractionToPercent_Click(object sender, EventArgs e)
{
double numerator = 0.00;
double denominator = 0.00;
double result;

try
{
numerator = double.Parse(txtNumerator.Text);
}
catch (FormatException)
{
MessageBox.Show("Invalid Numerator", "Percentage Conversion");
}

try
{
denominator = double.Parse(txtDenominator.Text);
}
catch (FormatException)
{
MessageBox.Show("Invalid Value to Convert", "Percentage Conversion");
}

result = (numerator / denominator) * 100;
txtPercentage2.Text = result.ToString("F");
}```
13. Double-click the third = button
14. Implement its event as follows:
```private void btnDecimalToPercent_Click(object sender, EventArgs e)
{
double value = 0.00;
double result;

try
{
value = double.Parse(txtDecimal1.Text);
}
catch (FormatException)
{
MessageBox.Show("Invalid Value to Convert", "Percentage Conversion");
}

result = value * 100;
txtPercentage3.Text = result.ToString("F");
}```
16. Double-click the last = button
17. Implement its event as follows:
```private void btnPercentToDecimal_Click(object sender, EventArgs e)
{
double value = 0.00;
double result;

try
{
value = double.Parse(txtPercentage4.Text);
}
catch (FormatException)
{
MessageBox.Show("Invalid Value to Convert", "Percentage Conversion");
}

result = value / 100;
txtDecimal2.Text = result.ToString("F");
}```
19. Double-click the Close button
20. Implement its event as follows:
```private void btnClose_Click(object sender, EventArgs e)
{
Close();
}```
21. To execute, press F5

22. Enter some values and click the = buttons