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Add examples of a spread element to the "Collection initializers" article #44045

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Jan 6, 2025
Merged

Add examples of a spread element to the "Collection initializers" article #44045

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9e6ad4f
Add example of spread operator for collection initializers
BartoszKlonowski Dec 20, 2024
8ef96f0
Inlcude the spread element example in the text
BartoszKlonowski Dec 20, 2024
579da7d
Include additional syntax for manually creating additional element
BartoszKlonowski Dec 20, 2024
a1970f4
Include spread element in full example code
BartoszKlonowski Dec 20, 2024
62d67da
Remove unnecessary System.Xml.Linq
BartoszKlonowski Dec 20, 2024
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8 changes: 8 additions & 0 deletions ...arp/programming-guide/classes-and-structs/object-and-collection-initializers.md
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Original file line number Diff line number Diff line change
Expand Up @@ -149,6 +149,14 @@ You can specify [null](../../language-reference/keywords/null.md) as an element

:::code language="csharp" source="./snippets/object-collection-initializers/BasicObjectInitializers.cs" id="ListInitializerWithNull":::

You can use a spread element to create one list that copies other list or lists.

:::code language="csharp" source="./snippets/object-collection-initializers/BasicObjectInitializers.cs" id="ListInitializerWithSpreadOperator":::

And include additonal elements along with using a spread element.

:::code language="csharp" source="./snippets/object-collection-initializers/BasicObjectInitializers.cs" id="ListInitializerWithSpreadOperatorAndAdditionalElement":::

You can specify indexed elements if the collection supports read / write indexing.

:::code language="csharp" source="./snippets/object-collection-initializers/BasicObjectInitializers.cs" id="DictionaryIndexerInitializer":::
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34 changes: 19 additions & 15 deletions ...de/classes-and-structs/snippets/object-collection-initializers/BasicObjectInitializers.cs
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Expand Up @@ -98,6 +98,14 @@ from p in products
};
// </SnippetListInitializerWithNull>

// <SnippetListInitializerWithSpreadOperator>
List<Cat> allCats = [.. cats, .. moreCats];
// </SnippetListInitializerWithSpreadOperator>

// <SnippetListInitializerWithSpreadOperatorAndAdditionalElement>
List<Cat> additionalCats = [.. cats, new Cat { Name = "Furrytail", Age = 5 }, .. moreCats];
// </SnippetListInitializerWithSpreadOperatorAndAdditionalElement>

// <SnippetDictionaryIndexerInitializer>
var numbers = new Dictionary<int, string>
{
Expand Down Expand Up @@ -182,15 +190,10 @@ public static void Main()
null
};

// Display results.
System.Console.WriteLine(cat.Name);
List<Cat> allCats = [.. cats, new Cat { Name = "Łapka", Age = 5 }, cat, .. moreCats];

foreach (Cat c in cats)
{
System.Console.WriteLine(c.Name);
}

foreach (Cat? c in moreCats)
// Display results.
foreach (Cat? c in allCats)
{
if (c != null)
{
Expand All @@ -203,13 +206,14 @@ public static void Main()
}
}
// Output:
//Fluffy
//Sylvester
//Whiskers
//Sasha
//Furrytail
//Peaches
//List element has null value.
// Sylvester
// Whiskers
// Sasha
// Łapka
// Fluffy
// Furrytail
// Peaches
// List element has null value.
}
// </SnippetFullExample>

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