Can I check if a variable can be cast to a specified type?

Question

I am trying to verify whether a variable that is passed can be converted to a specific type. I have tried the following but can't get it to compile so I assume I'm going about it the wrong way (I'm new to C#)

string myType = "System.Int32"; string myValue = "42";  bool canBeCast = false;  try {   // try to convert the value to it's intended type to see if it's valid.   var result = (Type.GetType(typeString))dataValue;   canBeCast = true; } catch {   canBeCast = false; } 

I'm basically trying to avoid a massive switch statement along the lines of

  switch(myType){     case "System.Int32":       try       {         var convertedValue = Convert.ToInt32(myValue);       }       catch (Exception)       {         canBeConverted = false;       }       break;     case "another type":       ...   } 

EDIT:

Ok, basically I have a db table of known input types that looks like:

CREATE TABLE [dbo].[MetadataTypes] (     [typeName]  VARCHAR (50)  NOT NULL,     [dataType]  VARCHAR (50)  NOT NULL,     [typeRegex] VARCHAR (255) NULL ); 

which may have data such as

"StartTime","System.DateTime",null "TicketId","System.String","$[Ff][0-9]{7}^" 

And the input to my function would be a KeyValuePair along the lines of

myInput = new KeyValuePair<string,string>("StartTime","31/12/2010 12:00"); 

I need to check that the value of the KeyValuePair is of the correct datatype expected by the MetaDataType.

EDIT FOR ANSWER:

Leon got really close to the solution I finally came up with.

For reference my function now looks like this:

public Boolean ValidateMetadata(KeyValuePair<string, string> dataItem) {    // Look for known metadata with name match   MetadataType type = _repository.GetMetadataTypes().SingleOrDefault(t => t.typeName == dataItem.Key);   if (type == null) { return false; }    // Get the data type and try to match to the passed in data item.   Boolean isCorrectType = false;   string typeString = type.dataType;   string dataValue = dataItem.Value;    try   {     var cValue = Convert.ChangeType(dataValue, Type.GetType(typeString));     isCorrectType = true;   }   catch   {     isCorrectType = false;   }    //TODO: Validate against possible regex here....                return isCorrectType;  } 

Answer 1

Use the "as" operator to attempt a cast:

var myObject = something as String;  if (myObject != null) {   // successfully cast } else {   // cast failed } 

If the cast fails, no exception is thrown, but the destination object will be Null.

EDIT:

if you know what type of result you want, you can use a helper method like this:

public static Object TryConvertTo<T>(string input) {     Object result = null;     try     {         result = Convert.ChangeType(input, typeof(T));     }     catch     {     }      return result; } 

Answer 2

Checkout this link: http://msdn.microsoft.com/en-us/library/scekt9xw(v=vs.71).aspx

The is operator is used to check whether the run-time type of an object is compatible with a given type. The is operator is used in an expression of the form:

if (expression is type){     // do magic trick } 

Something you can use?