Function

The Wind Chill Project Write a program that calculates the wind chill temperature Find a formula - UST Today Weather Web site www.usatoday.com/weather/wchilform.htm Inputs: Wind Speed and Temperature Outputs: Wind Chill Temperature

The Wind Chill Project Orginal formula Visual Basic statement WC = 0.0817(3.71(V **0.5) + 5.81 - 0.25V)(T - 91.4) + 91.4 Visual Basic statement WC = 0.0817 * (3.71 * Sqr(V) + 5.81 -(0.25 * V)) * (T - 91.4) + 91.4

Functions Function - unit of code that returns a value Build-in Functions Sqr - square root Rnd - random number generator Int - returns integer portion of a number Val - converts a string to a value

Functions Locating built-in functions Programmer-written functions Open the Functions online reference book or search for a function by name Programmer-written functions Write your own functions using the Function statement

The Function Statement Private Function function-name (argument1, argument2....) statements End Function Where Private or Public is required Function indicates the beginning of a function function-name is the name that will be used to call the function ( ) parentheses are required around the argument list argument1, argument2 are optional variables needed to perform the calculation or actions needed for the function End Function indicates the end of the function

WindChill Function Private Function WindChill( ) ‘Purpose: Calculate the Wind Chill ‘Reference: National Weather Service Dim V As Integer ‘Wind Speed Velocity Dim T AS Integer ‘Temperature V = hsbSpeed.Value T = hsbTemperature.Value WindChill = 0.0817 * (3.71 * Sqr(V) _ +5.81 - (0.25*V)) * (T-91.4)+91.4 End Function

WindChill Function Private Sub cmdCalculate_Click() WC = WindChill() When the cmdCalculate button is clicked, the WindChill function is executed Private Sub cmdCalculate_Click() WC = WindChill() txtWindChill.Text = Cint(WC) End Sub

The Wind Chill Project using Functions and Procedures Hands-On Exercise 1 (p.103-114) Create a New Project Create the Controls for Temperature Input Create the Controls for Wind Speed Input Create the Controls for Wind Chill Output Create the Image Control Add Banner Comments Add the Wind Chill Function Add Temperature and Speed Procedures Save, Run, Test your Project

End of Lecture