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Cannot Modify Result Unboxing Conversion C#

This is the origin of the saying, "Mutable structs are evil". –Servy Jun 24 '13 at 16:42 1 @Servy But what if I don't throw away the copy, and I Thursday, October 01, 2009 3:45 PM 0 Sign in to vote Even with a dictionary, you can't modify a field of a stored value. If TValue is a value type, then dict[i] would also return a copy and not a reference to the value. Boxing does not come into play when casting a reference type, unless you cast a reference type back to a value type (see above.) Example: string s = (string)myObjectThatCanBeConvertedToAString; Or, you Check This Out

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With C# you can access only instances of class Osto directly with your generic list List. Ask a question Quick access Forums home Browse forums users FAQ Search related threads Remove From My Forums Answered by: Cannot modify the result of an unboxing conversion Archived Forums V Example: object o = intValue; // boxing int i = (int)o; // unboxing Boxing also comes into play when casting to an interface. Appreciate your patience and expertise.

asked 5 years ago viewed 2471 times active 4 years ago Upcoming Events 2016 Community Moderator Election ends Nov 22 Linked 66 What is the difference between casting and conversion? Cheers, Facebook Twitter YouTube malmaa View Public Profile Send a private message to malmaa Find More Posts by malmaa 01-18-2010, 08:00 AM #5 Ralph Senior Member Join Date: Can clients learn their time zone on a network configured using RA? I cant see why?

Dear Jon! Follow (1) or (2)? My Code: // struc containing info of stops, limits, IOrders of Positions that opened at an instance privatestruct Osto {publicdouble op;publicdouble st;public DateTime tm;public IOrder oe1;public IOrder oe2;public IOrder os1;public IOrder https://bytes.com/topic/c-sharp/answers/665395-cannot-modify-result-unboxing-conversion Would we find alien music meaningful?

The time now is 07:04 PM. C# Copy class TestUnboxing { static void Main() { int i = 123; object o = i; // implicit boxing try { int j = (short)o; // attempt to unbox System.Console.WriteLine("Unboxing Firstly, having a mutable struct is generally a bad idea - it's likely to bite you sooner or later. Example: IDisposable disp = (IDisposable)someDisposableObject; share|improve this answer edited Jul 17 '12 at 13:25 Shane Fulmer 5,22332438 answered Jan 19 '11 at 11:53 Lasse V.

From the context of your reply I suppose it means that value type variables such as int and struct are inherently mutable, i.e. I got the method of changing the values of List containing class objects. Learning resources Microsoft Virtual Academy Channel 9 MSDN Magazine Community Forums Blogs Codeplex Support Self support Programs BizSpark (for startups) Microsoft Imagine (for students) United States (English) Newsletter Privacy & cookies more hot questions question feed lang-cs about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Arts Culture / Recreation

Marked as answer by HarryBedi Thursday, October 01, 2009 3:46 PM Thursday, October 01, 2009 3:41 PM All replies 1 Sign in to vote There's a good reason it doesn't let his comment is here var sum = 0; for (var j = 1; j < 5; j++) { // The following statement causes a compiler error: Operator // '*' cannot be applied to operands of But that still would be a new value. if I remove the boxing the error is cannot convert type System.Collections.Hashtable to VCVDemo.VCV Could someone please tell me where I am going wrong in the casting of this subroutine Thanks,

It's analogue to Location.X = 10. If you change the value of a field within that copy, it won't do what you want. Thank you so much for your help. http://ecoflashapps.com/cannot-modify/cannot-modify-the-result-of-an-unboxing-conversion-net.html The language specification is the definitive source for C# syntax and usage.Related SectionsFor more information:Reference TypesValue TypesC# Language SpecificationFor more information, see the C# Language Specification.

To fix this, declare a new value-type variable to store the intermediate expression, and assign the result of the unboxing conversion to that variable.The following code generates CS0455. file streams). Can I hide disabled users in the User Manager?

Each element j is boxed when // you add j to mixedList.

Visit our UserVoice Page to submit and vote on ideas! How to gain confidence with new "big" bike? However, in the case of the struct type element, C# won't allow it. As soon as you removed the no longer needed class instances from the list and there are no other references to these instances, you just can forget them without anxiety.

But you can always benefit from knowing more. He's changed to using classes now, so he will be able to. Thursday, October 01, 2009 3:24 PM 0 Sign in to vote for (int i = 0; i < instruments.Count; i++) { ((VCV)htVCV[i]).Mean = Mathematik.Statistics.Mean((double[])htVCV[i]); } I changed over the struct to http://ecoflashapps.com/cannot-modify/cannot-modify-the-result-of-an-unboxing-conversion-c.html Thread Tools Display Modes 01-17-2010, 12:32 PM #1 malmaa Member Join Date: Dec 2009 Posts: 67 Thanks: 0 Thanked 0 times in 0 posts Modifying elements of an ArrayList-

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