C# storing data in data structure?

Anonymous classes and implicitly typed arrays make code shorter by doing away with the need for class templates and explicit types in source code A big drawback of this feature is elements are read-only.

Anonymous classes and implicitly typed arrays make code shorter by doing away with the need for class templates and explicit types in source code. A big drawback of this feature is elements are read-only. No additional code is missing from this example, except to paste it into your source file.

A concise, anonymous data structure // Strongly-typed anonymous data structure. Var allData = new { // array of parts new { Num = 1, Details = new { // each part is keyed by object num new {KeyChar = 'a', StringValue = "10"} , // key/value pair details new {KeyChar = 'b', StringValue = "xyz"} , new {KeyChar = 'c', StringValue = "40"} } }, new { Num = 12, Details = new { new {KeyChar = 'a', StringValue = "20"} , new {KeyChar = 'b', StringValue = "os"} } }, new { Num = 8, Details = new { new {KeyChar = 'n', StringValue = "etc..."} } } }; The Types are automatically inferred by your consistent data declarations and generated into IL by the C# 3. X+ compiler.

Sample Usage iterating over your data structure and printing it .... foreach (var part in allData) { Console. WriteLine("Object #" + part. Num + " contains the details: "); foreach (var detail in part.

Details) Console. WriteLine(" - key: " + detail. KeyChar + ", value: " + detail.

StringValue); } Stipulations var, for implicitly typed variables, cannot be used at the class scope (i.e. To make fields) - it is restricted to method scope (i.e. As local variables).

There are some things to watch out for when using anonymous types, for example: Can't return anonymous type from method? Really? The MSDN documentation describes some additional behaviour and "Gotchas".

- Anonymous instances are read-only, so you will need a different way to store and persist modifications. This may render it useless for your requirements. However, it was fun to include this answer as an option because I learned something new today if nothing else.

:) Edit/Update: Writable version (modification to make an equivalent writable data structure) An equivalent writable version of the above data structure is the following, using System.Collections. Generic;: // Initialization (present data is read/writable) Dictionary> manageableData = new Dictionary>() { {1, new List() { new Detail {KeyChar = 'a', StringValue="10"}, new Detail {KeyChar = 'b', StringValue="xyz"}, new Detail {KeyChar = 'c', StringValue="40"} } }, {12, new List() { new Detail {KeyChar = 'a', StringValue="20"}, new Detail {KeyChar = 'b', StringValue="os"} } } }; // Can continue populating after initialization. E.g... manageableData.

Add(8, new List() { new Detail {KeyChar = 'n', StringValue="etc..."}, new Detail {KeyChar = 'z', StringValue="etc..."} }); A small helper class is declared to make initialization of detail data more readable; the Detail helper class replaces what could simply be KeyValuePair. According to taste. Public class Detail { public char KeyChar { get; set; } public string StringValue { get; set; } } ... effectively allows us to use new Detail {KeyChar = 'b', StringValue="xyz"} for init of detail items instead of new KeyValuePair('b', "xyz").

Sample Usage iterating over your data structure and printing it .... foreach (var part in manageableData) { Console. WriteLine("Object #" + part. Key + " contains the details: "); foreach (var detail in part.

Value) Console. WriteLine(" - key: " + detail. KeyChar + ", value: " + detail.

StringValue); } Another variation on Writable data structure (less abstract) (no unneeded abstraction - just raw collections) Without the custom Detail class, you'd nest your dictionaries like Dictionary data2 = new Dictionary() { {1, new Dictionary() { {'a', "10"}, {'b', "xyz"}, {'c', "40"} } } }; data2. Add(8, new Dictionary() { {'n', "etc..."}, {'z', "etc..."} }); // SAMPLE USAGE: // Once again, very minor changes to the mechanism of accessing the data structure: foreach (var part in data2) { Console. WriteLine("Object #" + part.

Key + " contains the details: "); foreach (var detail in part. Value) Console. WriteLine(" - key: " + detail.

Key + ", value: " + detail. Value); } Name "Aliasing" for readability This is the plain nested dictionary scenario to store file objects and attributes. // initialize Dictionary data1 = new Dictionary() { {1, new Dictionary() { {'a', "10"}, {'b', "xyz"}, {'c', "40"} }} }; // populate data1.

Add(8, new Dictionary() { {'n', "etc..."}, {'z', "etc..."} }); Making a more Descriptive/Readable Version There are ways to make nested data structures more readable. Here's one sample to show some readability differences. Likely this isn't the smartest way because it adds a couple of Types just for the sake of aliasing but nonetheless... This is the exact same data structure as above but using "aliased" names: // initialize FileObjects data2 = new FileObjects() { {1, new ObjectAttributes() { {'a', "10"}, {'b', "xyz"}, {'c', "40"} }} }; // populate data2.

Add(8, new ObjectAttributes() { {'n', "etc..."}, {'z', "etc..."} }); The following "alias" definitions effectively rename the original Generics (through inheritance) to more descriptive types and hide the Type Parameters. Public class ObjectAttributes : Dictionary { } public class FileObjects : Dictionary { } Likely you'd need more nested data before this type of approach becomes viable.

A Dictionary> Edit: if you only have 'a' 'b' 'c' as the keys, you'd just use string rec = new string3 instead of a dictionary.

– Mitch Wheat Jan 4 '10 at 6:28 @Mitch a int holds the index numbers 1, 12, 8 etc – Yin Zhu Jan 4 '10 at 6:30 @Mitch, his outer Dictionary is keyed on int, and all three items on the left are ints. – ProfK Jan 4 '10 at 6:38.

Data content itself is just one aspect of data structure choice. A more important guideline is how you will create, manipulate, and access the data. List> will handle ordering if you want to access 1, 2, 3, etc.. in an ordered fashion and allow the second level to be any type of content you want.

Dictionary> would allow you to do fast lookups of any top level 1, 2, 3, etc... and would assume that the a / 10, be / xyz, etc... are always encoded as strings. It would help if you told us how you were using this data.

Raw structure you could use: Dictionary> //or Dictionary> //the more common construct, or Dictionary> //would require casting on some objects This probably won't be optimal for your situation though, depending on how you intend to search/access this. Depending on the meaning of your data a specific class implementation and a Dictionary implementation might work better.

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