#### Writing the program code and testing the application

We will use the following C# code for handling events:

private void FormConverter_Load(object sender, EventArgs e)
{
ConvertCurrency();
}

private void numericUpDownAmount_ValueChanged(object sender, EventArgs e)
{
ConvertCurrency();
}

private void numericUpDownAmount_KeyUp(object sender, KeyEventArgs e)
{
ConvertCurrency();
}


All of the caught events call out the method ConvertCurrency(), which converts the given sum from levs to euro and shows the result int the green box.

We have to wrtite the code (program logic) for converting from levs to euro:

private void ConvertCurrency()
{
var amountBGN = this.numericUpDownAmount.Value;
var amountEUR = amountBGN * 1.95583m;
this.labelResult.Text =
amountBGN + " BGN = " +
Math.Round(amountEUR, 2) + " EUR";
}


In the end we start the project with [Ctrl+F5] and test if it works correctly.

If you have any problems with the example above, watch the video in the begging of this chapter. There, the application is being built live, step by step, with a lot of explanations. Or ask a question in the forum of SoftUni: https://softuni.bg/forum.