Stephens' C# Programming with Visual Studio® 2010 24-Hour Trainer

264

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LESSON 22 Preventing Bugs

// Calculate the average.

decimal averageSalary = AverageSalary(salaries);

// Display the result.

averageTextBox.Text = averageSalary.ToString(“C”);

}

catch (Exception ex)

{

averageTextBox.Clear();

MessageBox.Show(ex.Message);

}

}

Again a real program shouldn’t let the user enter salaries as string like this because

the user could enter invalid values.

Make the

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AverageSalary method validate its inputs by asserting that the array has a reason-

able number of elements and that the salaries are reasonable. (Assume you’re not working on

Wall Street so salaries are at least $10,000 and less than $1 million.) Also validate the average.

1. You can use code similar to the following:

// Calculate the average of this array of salaries.

private decimal AverageSalary(decimal[] salaries)

{

// Sanity checks.

if (salaries.Length < 1)

{

throw new ArgumentOutOfRangeException(“salaries”,

“AverageSalary method cannot calculate average “ +

“salary for an empty array.”);

}

Debug.Assert(salaries.Length < 100, “Too many salaries.”);

for (int i = 0; i < salaries.Length; i++)

{

Debug.Assert(salaries[i] >= 10000, “Salary is too small.”);

Debug.Assert(salaries[i] < 1000000, “Salary is too big.”);

}

// Calculate the result.

decimal total = 0;

for (int i = 0; i < salaries.Length; i++)

{

total += salaries[i];

}

decimal result = total / salaries.Length;

// Validate the result.