Rick Caminiti dotCOM » Short-Circuiting in C# with OrElse Operator – Rick Caminiti dotCom

Short-Circuiting in C# with OrElse Operator

NothingMan — Fri, 12 Jun 2009 20:33:07 +0000

I’d heard about short-circuiting before but had never seen it actually applied. I guess the main benefit of the OrElse operator is that it can improve performance if the “bypassed” condition is cumbersome. It’s basically an OR statement, but if the first expression evaluates as TRUE, it doesn’t need to evaluate the second expression. Normally, both expressions would be evaulated, but in reality, if the first one is TRUE, the whole condition is TRUE, so why evaluate the second one, right?

result


Required. Any Boolean expression. 
expression1 
Required. Any Boolean expression. 
expression2 
Required. Any Boolean expression.

If expression1 is	And expression2 is	Then result is
True	(not evaluated)	True
False	True	True
False	False	False

It’s this simple:

Dim A As Integer = 10 Dim B As Integer = 8 Dim C As Integer = 6 Dim myCheck As Boolean myCheck = A > B OrElse B > C ' True. Second expression is not evaluated. myCheck = B > A OrElse B > C ' True. Second expression is evaluated. myCheck = B > A OrElse C > B ' False.

If MyFunction(5) = True OrElse MyOtherFunction(4) = True Then ' If MyFunction(5) is True, MyOtherFunction(4) is not called. ' Insert code to be executed. End If

WTF is an Enum?

NothingMan — Thu, 04 Jun 2009 14:01:19 +0000

I’m a data-person but I like to change it up every now and then jump into some real code. I was dabbling in C# last week and was looking into Enums. I had heard about them a lot but never REALLY knew what they were or how they were constructed, so I forced myself to figure out WTF they were.

In computer programming, an enumerated type (also called enumeration or enum) is a data type consisting of a set of named values called elements, members or enumerators of the type. The enumerator names are usually identifiers that behave as constants in the language. A variable that has been declared as having an enumerated type can be assigned any of the enumerators as a value.

For example, the four suits in a deck of playing cards may be four enumerators named CLUB, DIAMOND, HEART, SPADE, belonging to an enumerated type named suits. If a variable V is declared having suits as its data type, one can assign any of those four values to it.

The enumerators are necessarily distinct, even though some languages may allow the same enumerator to be listed twice in the type’s declaration. The enumerators need not be complete or compatible in any sense. For example, an enumerated type called color may be defined to consist of the enumerators RED, GREEN, ZEBRA, and MISSING. In some languages, the declaration of an enumerated type also defines an ordering of its members.

Some enumerator types may be built into the language. The Boolean type, for example is often a pre-defined enumeration of the values FALSE and TRUE. Many languages allow the user to define new enumerated types.

Here’s a quick look at how to create an Enum and how to use them.
using System;

// declares the enum public enum Volume { Low, Medium, High } // demonstrates how to use the enum class EnumSwitch { static void Main() { // create and initialize // instance of enum type Volume myVolume = Volume.Medium; // make decision based // on enum value switch (myVolume) { case Volume.Low: Console.WriteLine("The volume has been turned Down."); break; case Volume.Medium: Console.WriteLine("The volume is in the middle."); break; case Volume.High: Console.WriteLine("The volume has been turned up."); break; } Console.ReadLine(); } }

Google Geocoding in SSIS

NothingMan — Wed, 20 May 2009 17:46:18 +0000

I have an old YouTube tutorial on how to use Google Geocoding within SSIS, but I lost all the downloadable scripts. I recently had a few people asking me if I could send them the scripts, so I deiceded to rewrite them.

Again, you can check out the YouTub video (it’s rough) for more details, just go to http://www.youtube.com/watch?v=HTSHzR-wSgc with this DISCLAIMER: This code was just thrown together and is quite ugly and my microphone was terrible, I usually sound much better than that :-)

In a nutshell, I sniped about 18,000 golfcourses off the web with a PHP script and got basic course information for all of them, including the address information. I wanted to use Google Maps to display these courses, so I thought I’d use Google Geocoding. Caution, they don’t like it when you hit them 1000 times per second, so I would recommend using a Sleep command in your code like I did so you can throttle it without getting kicked off.

So, I have an OLE Source task that reads from my database. I created a Derived Column task to create placeholders for latitude, longitude, and level of accuracy. I created a Script Component and selected street, city, state, and zip as input columns and added lat, long, and accuracy as read/write columns.

Open the script editor, add a reference to System.Web, then create a new class called Google GeoCode, or whatever the heck you want to call it and paste in this code:

Option Strict Off


''' Might need this, might not
Imports System
Imports System.Data
Imports System.Math
Imports System.Net
Imports System.Web
Imports System.IO
Namespace GoogleGeoCoder
    Public Interface ISpatialCoordinate
        Property latitude() As Double
        Property longitude() As Double
    End Interface
    ''' 
    
    ''' Coordiate structure. Holds Latitude and Longitude.    
    ''' 
    
    Public Structure Coordinate
        Implements ISpatialCoordinate
 
        Private _latitude As Double
        Private _longitude As Double
 
        Public Sub New(ByVal lattitude As Double, ByVal longitude As Double)
            _latitude = lattitude
            _longitude = longitude
        End Sub
 
        Public Property latitude() As Double Implements ISpatialCoordinate.latitude
            Get
                Return _latitude
            End Get
            Set(ByVal value As Double)
                _latitude = value
            End Set
        End Property
 
        Public Property longitude() As Double Implements ISpatialCoordinate.longitude
            Get
                Return _longitude
            End Get
            Set(ByVal value As Double)
                _longitude = value
            End Set
        End Property
 
    End Structure
    Public Class GeoCode
        Const _googleUri As String = "http://maps.google.com/maps/geo?q="
        Const _googleKey As String = "yourgooglekeyhere"  ' get your own        
        Const _outputType As String = "csv"
        Private Shared Function GetGeoCodeUri(ByVal address As String) As Uri
            address = HttpUtility.UrlEncode(address)
            Return New Uri(String.Format("{0}{1}&output={2}&key={3}", _googleUri, address, _outputType, _googleKey))
        End Function
        ''' 
        
        ''' Gets a Coordinate from a address.        
        ''' 
        
        ''' An address.        
        '''         
        ''' 1600 Amphitheatre Parkway Mountain View, CA 94043        
        '''         
        '''         
        ''' A spatial coordinate that contains the latitude and longitude of the address.        
        Public Shared Function GetCoordinates(ByVal address As String) As Coordinate
            Dim client As WebClient = New WebClient()
            Dim uri As Uri = GetGeoCodeUri(address)
            Dim geoCodeInfo As String()
            'The first number is the status code,             
            'the second is the accuracy,             
            'the third is the latitude,             
            'the fourth one is the longitude.            
            Try
                geoCodeInfo = client.DownloadString(uri).Split(",")
                Return New Coordinate(Convert.ToDouble(geoCodeInfo(2)), Convert.ToDouble(geoCodeInfo(3)))
            Catch ex As Exception
                Return New Coordinate(0.0, 0.0)
            End Try
        End Function
    End Class
End Namespace

Save it and then go back to the main script and add Import that class (see code). Notice, the way I’m getting the level of accuracy with my ugly nested IF statements isn’t the prettiest way to do this, use your imagination. Copy in this code into the Main Script:


' Microsoft SQL Server Integration Services user script component
' This is your new script component in Microsoft Visual Basic .NET
' ScriptMain is the entrypoint class for script components
 
Imports System
Imports System.Data
Imports System.Math
Imports Microsoft.SqlServer.Dts.Pipeline.Wrapper
Imports Microsoft.SqlServer.Dts.Runtime.Wrapper
Imports ScriptComponent_4a8732cababc49a999159a91c737082a.GoogleGeoCoder
 
Public Class ScriptMain
    Inherits UserComponent
 
    Public Overrides Sub Input0_ProcessInputRow(ByVal Row As Input0Buffer)
 
        Dim coordinate As Coordinate = GeoCode.GetCoordinates(Row.street & ", " & Row.city & ", " & Row.state & ", " & Row.zip)
 
        If ((coordinate.latitude <> 0) And (coordinate.longitude <> 0)) Then
            Row.lat = Convert.ToDecimal(coordinate.latitude)
            Row.long = Convert.ToDecimal(coordinate.longitude)
            Row.acc = 1
        Else
            coordinate = GeoCode.GetCoordinates(Row.city & ", " & Row.state & ", " & Row.zip)
            If ((coordinate.latitude <> 0) And (coordinate.longitude <> 0)) Then
                Row.lat = Convert.ToDecimal(coordinate.latitude)
                Row.long = Convert.ToDecimal(coordinate.longitude)
                Row.acc = 2
            Else
                coordinate = GeoCode.GetCoordinates(Row.zip)
                If ((coordinate.latitude <> 0) And (coordinate.longitude <> 0)) Then
                    Row.lat = Convert.ToDecimal(coordinate.latitude)
                    Row.long = Convert.ToDecimal(coordinate.longitude)
                    Row.acc = 3
                Else
                    coordinate = GeoCode.GetCoordinates(Row.city & ", " & Row.state)
                    If ((coordinate.latitude <> 0) And (coordinate.longitude <> 0)) Then
                        Row.lat = Convert.ToDecimal(coordinate.latitude)
                        Row.long = Convert.ToDecimal(coordinate.longitude)
                        Row.acc = 4
                    Else
                        coordinate = GeoCode.GetCoordinates(Row.state)
                        If ((coordinate.latitude <> 0) And (coordinate.longitude <> 0)) Then
                            Row.lat = Convert.ToDecimal(coordinate.latitude)
                            Row.long = Convert.ToDecimal(coordinate.longitude)
                            Row.acc = 5
                        End If
                    End If
                End If
            End If
        End If
    End Sub
 
End Class