Better way to cast object to int

Question

This is probably trivial  but I can t think of a better way to do it  I have a COM object that returns a variant which becomes an object in C   The only way I can get this into an int is   int test   int Parse string Format   0    myobject     Is there a cleaner way to do this  Thanks

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You can first cast object to string and then cast the string to int  for example  string str myobject   myobject ToString    int int myobject   int Parse str myobject    this worked for me

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I am listing the difference in each of the casting ways  What a particular type of casting handles and it doesn t          object to int        does not handle null        does not handle NAN   102art54          convert value to integar     int intObj    int obj          handles only null or number     int  nullableIntObj    int  obj     null     Nullable lt int gt  nullableIntObj1    Nullable lt int gt  obj     null        best way for casting from object to nullable int       handles null        handles other datatypes gives null  sadfsdf      result null     int  nullableIntObj2   obj as int            string to int         does not handle null  throws exception         does not string NAN   102art54    throws exception         converts string to int   26236          accepts string value     int iVal3   int Parse  10120       throws exception value cannot be null          handles null converts null to 0        does not handle NAN   102art54    throws exception         converts obj to int   26236       int val4   Convert ToInt32  10120             handle null converts null to 0        handle NAN   101art54   converts null to 0        convert string to int   26236       int number       bool result   int TryParse value  out number        if  result                   converted value           else                  number o p   0

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Convert ToInt32 myobject    This will handle the case where myobject is null and return 0  instead of throwing an exception

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var intTried   Convert ChangeType myObject  typeof int   as int

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Use Int32 TryParse as follows     int test    bool result   Int32 TryParse value  out test     if  result           Console WriteLine  Sucess                   else          if  value    null  value             Console WriteLine  Failure

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The cast  int  myobject should just work   If that gives you an invalid cast exception then it is probably because the variant type isn t VT I4  My bet is that a variant with VT I4 is converted into a boxed int  VT I2 into a boxed short  etc    When doing a cast on a boxed value type it is only valid to cast it to the type boxed   Foe example  if the returned variant is actually a VT I2 then  int   short  myObject should work   Easiest way to find out is to inspect the returned object and take a look at its type in the debugger  Also make sure that in the interop assembly you have the return value marked with MarshalAs UnmanagedType Struct

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There s also TryParse   From MSDN   private static void TryToParse string value             int number        bool result   Int32 TryParse value  out number         if  result                   Console WriteLine  Converted   0   to  1     value  number                          else                  if  value    null  value                 Console WriteLine  Attempted conversion of   0   failed    value

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Strange  but the accepted answer seems wrong about the cast and the Convert in the mean that from my tests and reading the documentation too it should not take into account implicit or explicit operators   So  if I have a variable of type object and the  boxed  class has some implicit operators defined they won t work   Instead another simple way  but really performance costing is to cast before in dynamic    int  dynamic myObject   You can try it in the Interactive window of VS   public class Test     public static implicit operator int Test v          return 12          int  object new Test     this will fail Convert ToInt32  object new Test      this will fail  int  dynamic  object new Test     this will pass

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int i   myObject myField CastTo lt int gt

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You have several options     int   mdash  Cast operator   Works if the object already is an integer at some level in the inheritance hierarchy or if there is an implicit conversion defined  int Parse   int TryParse    mdash  For converting from a string of unknown format  int ParseExact   int TryParseExact    mdash  For converting from a string in a specific format Convert ToInt32     mdash  For converting an object of unknown type   It will use an explicit and implicit conversion or IConvertible implementation if any are defined  as int   mdash  Note the      The as operator is only for reference types  and so I used     to signify a Nullable lt int gt    The  as  operator works like Convert To        but think TryParse   rather than Parse    it returns null rather than throwing an exception if the conversion fails    Of these  I would prefer  int  if the object really is just a boxed integer   Otherwise use Convert ToInt32   in this case   Note that this is a very general answer   I want to throw some attention to Darren Clark s response because I think it does a good job addressing the specifics here  but came in late and wasn t voted as well yet   He gets my vote for  accepted answer   anyway  for also recommending  int   for pointing out that if it fails  int  short  might work instead  and for recommending you check your debugger to find out the actual runtime type

User · Answer

Maybe Convert ToInt32   Watch out for exception  in both cases

[c#] Better way to cast object to int

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