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Creating a Switch function that works for non-integral types

, 4 Jun 2007 CPOL
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A Switch function that works for non-integral types.

Introduction

Often when machines communicate with humans there is the need of switch statements. "The switch statement is a control statement that handles multiple selections and enumerations by passing control to one of the case statements within its body" (MSDN). These cases must always be constants and of an integral type. That means that doubles and floats can't be used and all other values must be constants.

This code uses templates and delegates to create a simple switch like structure that can be used for any type of case. The cases are sorted in a SortedList<TKey, TValue>.

The code uses anonymous methods to do the work in the case statements.

Using the code

In the sample code below, a message box is shown for each case.

Switch<string> switcher = new Switch<string>(); //Create Object
switcher.AddCase("Hello", delegate(object[] args)//Add cases
    { MessageBox.Show("Hello"); });
switcher.AddCase("Goodbye", delegate(object[] args)
    { MessageBox.Show("Goodbye"); });
switcher.AddCase("Morning", delegate(object[] args)
    { MessageBox.Show("Morning"); });
switcher.AddCase("Evening", delegate(object[] args)
    { MessageBox.Show("Evening"); });
switcher.AddCase("Afternoon", delegate(object[] args)
    { MessageBox.Show("Afternoon"); });
switcher.AddDefault(delegate (object [] args)
    { MessageBox.Show("Default"); });//Add a default case.
switcher.DoSwitch(StringTextBox.Text); //Do Switch

I made a class for doubles also. This version allows you to give a tolerance of how much the value can vary.

DoubleSwitch switcher = new DoubleSwitch();//Create Object
switcher.AddCase(1, delegate(object[] args)//Add cases
    { MessageBox.Show("1"); });
switcher.AddCase(2, delegate(object[] args)
    { MessageBox.Show("2"); });
switcher.AddCase(2.5, delegate(object[] args)
    { MessageBox.Show("2.5"); });
switcher.AddCase(3, delegate(object[] args)
    { MessageBox.Show("3"); });
switcher.AddCase(1000, delegate(object[] args)
    { MessageBox.Show("1000"); });
switcher.AddDefault(delegate (object [] args)
    { MessageBox.Show("Default"); });//Add a default case
switcher.DoSwitch((double) DoubleTextBox.Value, 0.1d); //Do switch.

The above code allows a tolerance of 0.1. That means that 2.59 will invoke the 2.5 case...

Further, specific classes are possible, they simply need to be derived from the base class and the function "DoSwitch" needs to be implemented.

Try the demo program to get a bit more of an idea...

History

This is the first version... Enjoy!

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Joe Sonderegger
Software Developer RUAG Aerospace
Switzerland Switzerland
No Biography provided

Comments and Discussions

 
GeneralMy vote of 2 Pinmemberjkersch5-Jan-10 12:47 
GeneralInteresting PinmemberMoim Hossain4-Jun-07 9:10 
GeneralRe: Interesting PinmemberNice Life4-Jun-07 20:05 
Generalbad example Pinmemberdimzon29-May-07 1:38 
GeneralRe: bad example PinmemberNice Life29-May-07 1:50 
GeneralString switch statements legal in C# PinmemberRudolf Jan Heijink29-May-07 1:08 
GeneralRe: String switch statements legal in C# PinmemberNice Life29-May-07 1:46 
GeneralRe: String switch statements legal in C# Pinmembertanwinking31-Jul-07 23:33 
GeneralRe: String switch statements legal in C# PinmemberJoe Sonderegger6-Aug-07 3:18 

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