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1. Top results related to how to initialize a dictionary in c# with example code

   • How to write an entity comparator in C# (with example code of first attempt)

     Top Answer

     Answered Aug 08, 2009 · 5 votes

     As is the code will not do what you are expecting.

     Try this simple test:

     -class A { public int Id { get; set; } public string Name { get; set; }}class B : A { public DateTime BirthDate { get; set; }}class ObjectComparer { public static void Show() { A a = new A(); B b = new B(); A a1 = new A(); Console.WriteLine(ObjectComparator.CompareProperties(a, b)); Console.WriteLine(ObjectComparator.CompareProperties(b, a)); Console.WriteLine(ObjectComparator.CompareProperties(a, a1)); }}

     You would expect it to return

     false

     false

     true

     but it returns

     false

     false

     false

     try changing the inner if to look like:

     -if (!object.Equals(newProperty.GetValue(newObject, null), oldProperty.GetValue(oldObject, null))) { return false; }

     You can also save some time in the case a and a1 both reference the same object by checking that in the begining of the method.

     -static class ObjectComparator { public static bool CompareProperties(T newObject, T oldObject) { if (object.Equals(newObject, oldObject)) { return true; } if (newObject.GetType().GetProperties().Length != oldObject.GetType().GetProperties().Length) { return false; } else { var oldProperties = oldObject.GetType().GetProperties(); foreach (PropertyInfo newProperty in newObject.GetType().GetProperties()) { try { PropertyInfo oldProperty = oldProperties.Single(pi => pi.Name == newProperty.Name); if (!object.Equals(newProperty.GetValue(newObject, null), oldProperty.GetValue(oldObject, null))) { return false; } } catch { return false; } } return true; } } }

     If you are concered with performance, you can cache the return of Type.GetProperties into a local variable during the lifetime of the method, since Reflection does not do that by itself at least up to version 3.5 SP1. In doing that you will drop GetProperties calls from four to two.

     If you are only expecting to compare objects of exactly the same type (or put another way not compare between base and derived instances), you can further reduce the calls of GetProperties to one.

     Hope this helps.

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     1/5

   • Initialize a Dictionary with values in C# 2.0

     Top Answer

     Answered Jul 19, 2013 · 10 votes

     But it doesn't work in C# 2.0. Is there any workaround for this without using Add or basing on an already existing collection?

     No. The closest I can think of would be to write your own DictionaryBuilder type to make it simpler:

     public class DictionaryBuilder<TKey, TValue>{ private Dictionary<TKey, TValue> dictionary = new Dictionary<TKey, TValue> dictionary(); public DictionaryBuilder<TKey, TValue> Add(TKey key, TValue value) { if (dictionary == null) { throw new InvalidOperationException("Can't add after building"); } dictionary.Add(key, value); return this; } public Dictionary<TKey, TValue> Build() { Dictionary<TKey, TValue> ret = dictionary; dictionary = null; return ret; }}

     Then you can use:

     Dictionary<string, int> x = new DictionaryBuilder<string, int>() .Add("Foo", 10) .Add("Bar", 20) .Build();

     This is at least a single expression still, which is useful for fields where you want to initialize at the point of declaration.

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     2/5

   • In C#: How to declare a generic Dictionary with a type as key and an IEnumerable<> of that type as value?

     Top Answer

     Answered Dec 01, 2017 · 21 votes

     You may not even need a dictionary to be able to do this - but that depends on your needs. If you only ever need 1 such list per type per appdomain (i.e. the "dictionary" is static), the following pattern can be efficient and promotes type-inference nicely:

     interface IBase {}-static class Container { static class PerType<T> where T : IBase { public static IEnumerable<T> list; } public static IEnumerable<T> Get<T>() where T : IBase => PerType<T>.list; public static void Set<T>(IEnumerable<T> newlist) where T : IBase => PerType<T>.list = newlist; public static IEnumerable<T> GetByExample<T>(T ignoredExample) where T : IBase => Get<T>(); }

     Note that you should think carefully before adopting this approach about the distinction between compile-time type and run-time type. This method will happily let you store a runtime-typed IEnumerable<SomeType> variable both under SomeType and -if you cast it- under any of SomeType's base types, including IBase, with neither a runtime nor compiletype error - which might be a feature, or a bug waiting to happen, so you may want an if to check that.

     Additionally, this approach ignores threading; so if you want to access this data-structure from multiple threads, you probably want to add some locking. Reference read/writes are atomic, so you're not going to get corruption if you fail to lock, but stale data and race conditions are certainly possible.

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     3/5

   • How to initialize a double array with various values using switch case in C#

     Top Answer

     Answered Jul 15, 2015 · 0 votes

     You were close, you just have to use new to initialize the arrays:

     double [] test1; int value; // Which I will get it from DBSwitch (value){case 1: test1 = new double[] {1, 0, 0,1}; break;case 2: test1 = new double[] {0, 0, 0,1}; break;case 3: test1 = new double[] {0, 0, 1,1}; break;case 4: test1 = new double[] {1, 0, 1,1}; break;}

     Check all answers on Stack Overflow

     4/5

   • How to use a string as code to initialize another string in C#?

     Top Answer

     Answered Nov 21, 2023 · 0 votes

     Use Regex Unescape(String input) method it returns a string of characters with any escaped characters converted to their unescaped form.

     Read official documentation here.

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     5/5

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2. learn.microsoft.com › en-us › dotnetHow to initialize a dictionary with a collection initializer - C#

   learn.microsoft.com › en-us › dotnet

   • Cached

   Mar 15, 2024 · Learn how to initialize a dictionary in C#, using either the Add method or an index initializer. This example shows both options. How to initialize a dictionary with a collection initializer - C# | Microsoft Learn

3. stackoverflow.com › questions › 17047602Proper way to initialize a C# dictionary with values

   stackoverflow.com › questions › 17047602

   • Cached

   With C# 6.0, you can create a dictionary in the following way: var dict = new Dictionary<string, int> { ["one"] = 1, ["two"] = 2, ["three"] = 3 }; It even works with custom types.

4. People also ask

   How to initialize a dictionary?

   • To initialize a dictionary, we can enclose each set of key-value in curly braces. Internally for each pair, the compiler makes a call to Dictionary’s Add() method. This is demonstrated below: 2. Index Initializer We can also initialize a dictionary using an index initializer, as shown below.

   Initialize a Dictionary in C# | Techie Delight

   www.techiedelight.com/initialize-dictionary-csharp/

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   How to initialize a dictionary in c# 6?

   • Another way to initialize a dictionary is object initializer introduced in C# 6: To add an item to a dictionary, we use the Add method. For example: This would add "Adam" and his age of 24 to the nameToAge dictionary. To remove an item from a dictionary, we use the Remove method. For example: This would remove "Adam" from the nameToAge dictionary.

   C# Dictionary: Complete Guide [2023] - Josip Miskovic

   josipmisko.com/posts/c-sharp-dictionary

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   How to create a dictionary in C#?

   • Dictionary Builder To create a dictionary with several entries, it’s better to create a type-safe DictionaryBuilder class. Then we can use Builder’s Add() method, which takes key-value pairs instead of a dictionary. The Add() associates key with value in the built dictionary. That’s all about initializing a Dictionary in C#.

   Initialize a Dictionary in C# | Techie Delight

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   How to initialize a dictionary with key-value pairs?

   • Besides creating an empty dictionary, we can also initialize a dictionary with some key-value pairs at the time of creation. Consider the following example: { "apple", 1 }, { "banana", 2 }, { "cherry", 3 } In this code snippet, we have created a dictionary, "dict", and initialized it with three key-value pairs.

   Guide to Initialize a Dictionary in C# | C# Tutorial

   www.gyata.ai/c-sharp/c-initialize-dictionary/

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5. stackoverflow.com › questions › 10998961c# - Adding values to a dictionary via inline initialization ...

   stackoverflow.com › questions › 10998961

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   Mar 10, 2017 · var moreNumbers = new Dictionary<int, string> { {19, "nineteen" }, {23, "twenty-three" }, {42, "forty-two" } }; This initializer example calls Add(TKey, TValue) to add the three items into the dictionary. These two different ways to initialize associative collections have slightly different behaviour because of the method calls the compiler ...

6. www.techiedelight.com › initialize-dictionary-csharpInitialize a Dictionary in C# | Techie Delight

   www.techiedelight.com › initialize-dictionary-csharp

   • Cached

   Apr 6, 2024 · 1. Collection Initializer. To initialize a dictionary, we can enclose each set of key-value in curly braces. Internally for each pair, the compiler makes a call to Dictionary’s Add() method. This is demonstrated below: Download Run Code. 2. Index Initializer. We can also initialize a dictionary using an index initializer, as shown below.

7. makolyte.com › csharp-initialize-a-dictionaryC# - Initialize a dictionary | makolyte

   makolyte.com › csharp-initialize-a-dictionary

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   Sep 12, 2023 · Option 1 – Initialize dictionary with values using indexer syntax. Here’s an example of initializing a dictionary with multiple key/value pairs using the indexer syntax (i.e. [key]=value): using System.Collections.Generic; var dictionary = new Dictionary< string, int >() { ["Bob"] = 1, ["Linda"] = 2, ["Teddy"] = 3}; Code language: C# (cs)

8. josipmisko.com › posts › c-sharp-dictionaryC# Dictionary: Complete Guide [2023] – Josip Miskovic

   josipmisko.com › posts › c-sharp-dictionary

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   Jan 26, 2023 · Initialization. To initialize a dictionary in C#, we first need to provide the type for the key and the type for the value. For example, for a dictionary that stores the name and age of a person, the initialization would be: C# Dictionary<string, int> nameToAge = new Dictionary<string, int>();

9. www.gyata.ai › c-sharp › c-initialize-dictionaryGuide to Initialize a Dictionary in C# | C# Tutorial

   www.gyata.ai › c-sharp › c-initialize-dictionary

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   Dec 8, 2023 · 1. Initializing an Empty Dictionary; The simplest way to initialize a dictionary in C# is to create an empty dictionary. The following code illustrates how to do this: // Define a new dictionary of string keys and integer values Dictionary dict = new Dictionary ();