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C# Dictionary Struct Key

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See Also System.Collections.Generic.Dictionary Class, System.Collections.Generic Namespace Dictionary.System.Collections.IDictionary.Add Method void IDictionary.Add(object key, object value) Summary This method is implemented to support the IDictionary interface. caching the result of calling GetHashcode) which don't change the perceivable state - no harm in that, although it would be unusual. -- Jon Skeet - http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet If Creating symlink for a file on Windows 7 gives error Can I hide disabled users in the User Manager? Are you suggesting that the compiler should start looking at the *implementation* of the method (which could be in a different assembly) to work out what to do? Check This Out

See Also System.Collections.Generic.Dictionary Class, System.Collections.Generic Namespace Dictionary(System.Collections.Generic.IDictionary) Constructor public Dictionary(IDictionary dictionary) Summary Initializes a new dictionary that contains elements copied from the specified dictionary, has sufficient capacity to accommodate the number That's the golden rule? See Also System.Collections.Generic.Dictionary Class, System.Collections.Generic Namespace Dictionary(int) Constructor public Dictionary(int capacity) Summary Initializes a new dictionary that is empty, has the specified initial capacity, and uses the default equality comparer. public static void Test() { MyClass[] classArray = new MyClass[1]; MyStruct[] structArray = new MyStruct[1]; MyInterface[] interfaceArray = new MyInterface[1]; List(1); List(1); List

C# Dictionary Struct Key

However, I am getting an error within Visual Studio Cannot modify the return value of System.Collections.Generic.List.this[int] because it is not a variable. At that point, if the language doesn't allow you to cast away And that impeaches the design of said API and should seriously call into question your decision to use it. What physical evidence exists that shows motor proteins "walking" within a cell? How can I remove an Online Account?

Exceptions Exception TypeCondition ArgumentNullExceptionkey is null . Code sample below. It makes it safer (which *is* the point of using "const"), but you can pass things by reference just fine without using "const". C# Structs Zytan May 14 '07 #18 P: n/a Jon Skeet [C# MVP] Peter Duniho I agree that this particular example is somewhat confusing.

Are you suggesting that the compiler should start looking at the *implementation* of the method (which could be in a different assembly) to work out what to do? C# Dictionary Struct Value In case a constructor doesn't exist with an overload to take your property (in this case X), you can use the object initializer (which will do all the magic behind the Other languages should use the same attribute, and methods from languages, that don't use that same attribute would be regarded as possibly changing the struct. http://stackoverflow.com/questions/13810743/cannot-modify-the-return-value-error-when-modifying-content-of-listt I still think C#'s designer's thoughts on how C++'s "const" only works because it can be cast away is 100% completely false.

Christof May 15 '07 #21 P: n/a Christof Nordiek "Samuel R. Dictionary C# Well, a *class* _isn't_ temporary. Structs are very performant when you constantly create and make redundant a lot of them... Well, you can still apply the same technique Bruce mentions: MyStruct x = list[index]; x.MethodThatChangesStructsFields(); list[index] = x; Pete May 14 '07 #6 P: n/a Jon Skeet [C# MVP] Zytan

C# Dictionary Struct Value

But, it's becoming obvious that the c# designers just want us to use reference types when we can, and everything in the langauge is based on this, and thus, it is https://social.msdn.microsoft.com/Forums/vstudio/en-US/b652efd2-b146-4207-bb81-5bebe2b37a57/efficiently-setting-the-a-value-type-in-a-dictionary?forum=netfxbcl For example, these two functions wind up compiled to be very different: const int i = 5; void Test1() { printf("%d", i); } int j = 5; void Test2() { printf("%d", C# Dictionary Struct Key Here's the code: foreach (KeyValuePair tile in tilesData) { if (tilesData[tile.Key].bgFrame >= tilesData[tile.Key].bgAnimation) { tilesData[tile.Key].bgFrame = 0; } else { tilesData[tile.Key].bgFrame++; } } It gives me compile arror: Error 1 Mutable Struct And even when you spend that time, frequently you reach a point where you're calling some third-party API that you don't have the freedom to change.

c# share|improve this question edited Dec 10 '12 at 23:03 Robert Harvey♦ 130k29225357 asked Dec 10 '12 at 22:56 Boardy 9,96754171284 add a comment| 1 Answer 1 active oldest votes up The capacity of a dictionary is the number of elements that dictionary can hold. I am still programming in C++ mode. See ads on Dice.com. C# Cannot Modify The Return Value Of Because It Is Not A Variable

Related 66Cannot modify the return value error c#0Not modifying list in loop but its throwing error Collection was modified; enumeration operation may not execute4Cannot modify the return value because it is I think I like that C++ is a little closer to reality, that is, how the computer does things. However, for value types exactly the same thing happens, and it does cause problems: the value is copied from the list onto the stack and returned as a function result. Fields should be private anyway, but yes, they should be private and probably all readonly, unless you want to set them from private methods called in the constructor.

Personally I'd strongly advise against having a mutable struct to start with, mind you... C# Struct Vs Class Property is just a get method. Beyond that, pass-by-const reference is more performant than pass-by-value for large data types.

Okay...well, I can agree that calling a method that changes a struct when the struct is temporary isn't useful.

Assembly mscorlib Library BCL Summary Represents a collection of key/value pairs that are organized based on the key. I see no reason to believe that would have the desired effect upon the object containing the Origin property. Should the linker be required to carry this flag around too, so that when you import a reference to a struct type not compiled with the current project, you still have B-Line Medical is seeking .NET Developers for exciting positions in medical product development in MD/DC.

HTH, Sam ------------------------------------------------------------ We're hiring! Things like overloading hiding certain type conversions, for example. In c++, if you have a method that doesn't change it, but you don't tell it specifically that it doesn't change it, then the compiler assumes that it COULD change it, And of course, likewise the compiler can't make optimizations requiring constant values based on non-constant values.

The latter seems really icky to me. –supercat Apr 25 '13 at 15:38 @supercat oh yes, overlooked that! Second, in the above example, the second line of code doesn't compile. Adverb for "syntax" It is possible to define metric spaces from pure topological concepts without the need to define a distance function?