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System.Comparison<T> F# Snippets #7537

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9 changes: 9 additions & 0 deletions samples/snippets/fsharp/VS_Snippets_CLR/List`1_SortComparison/fs/fs.fsproj
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<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net6.0</TargetFramework>
</PropertyGroup>
<ItemGroup>
<Compile Include="source.fs" />
</ItemGroup>
</Project>
66 changes: 66 additions & 0 deletions samples/snippets/fsharp/VS_Snippets_CLR/List`1_SortComparison/fs/source.fs
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// <Snippet1>
open System

let compareDinosByLength (x: string) (y: string) =
match x with
| null when isNull y ->
// If x is null and y is null, they're equal.
0
| null ->
// If x is null and y is not null, y is greater.
-1
| _ when isNull y->
// If x is not null and y is null, x is greater.
1
| _ ->
// If x is not null and y is not null, compare the lengths of the two strings.
let retval = x.Length.CompareTo y.Length

if retval <> 0 then
// If the strings are not of equal length, the longer string is greater.
retval
else
// If the strings are of equal length, sort them with ordinary string comparison.
x.CompareTo y

let display list =
printfn ""
for s in list do
if isNull s then
printfn "(null)"
else
printfn $"\"%s{s}\""


let dinosaurs = ResizeArray()
dinosaurs.Add "Pachycephalosaurus"
dinosaurs.Add "Amargasaurus"
dinosaurs.Add ""
dinosaurs.Add null
dinosaurs.Add "Mamenchisaurus"
dinosaurs.Add "Deinonychus"
display dinosaurs

printfn "\nSort with generic Comparison<string> delegate:"
dinosaurs.Sort compareDinosByLength
display dinosaurs


// This code example produces the following output:
//
// "Pachycephalosaurus"
// "Amargasaurus"
// ""
// (null)
// "Mamenchisaurus"
// "Deinonychus"
//
// Sort with generic Comparison<string> delegate:
//
// (null)
// ""
// "Deinonychus"
// "Amargasaurus"
// "Mamenchisaurus"
// "Pachycephalosaurus"
// </Snippet1>
64 changes: 64 additions & 0 deletions samples/snippets/fsharp/VS_Snippets_CLR_System/system.comparison`1/fs/comparisont1.fs
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// <Snippet1>
open System

type CityInfo =
{ City: string
Country: string
Population: int }

static member CompareByName city1 city2 =
String.Compare(city1.City, city2.City)

static member CompareByPopulation city1 city2 =
city1.Population.CompareTo city2.Population

static member CompareByNames city1 city2 =
String.Compare(city1.Country + city1.City, city2.Country + city2.City)

let display cities =
printfn $"""{"City",-20} {"Country",-25} {"Population",10}"""
for city in cities do
printfn $"{city.City,-20} {city.Country,-25} {city.Population,10:N0}"
printfn ""

let NYC = { City = "New York City"; Country = "United States of America"; Population = 8175133 }
let Det = { City = "Detroit"; Country = "United States of America"; Population = 713777 }
let Paris = { City = "Paris"; Country = "France"; Population = 2193031 }
let cities = [| NYC; Det; Paris |]
// Display ordered array.
display cities

// Sort array by city name.
Array.Sort(cities, CityInfo.CompareByName)
display cities

// Sort array by population.
Array.Sort(cities, CityInfo.CompareByPopulation);
display cities

// Sort array by country + city name.
Array.Sort(cities, CityInfo.CompareByNames);
display cities


// The example displays the following output:
// City Country Population
// New York City United States of America 8,175,133
// Detroit United States of America 713,777
// Paris France 2,193,031
//
// City Country Population
// Detroit United States of America 713,777
// New York City United States of America 8,175,133
// Paris France 2,193,031
//
// City Country Population
// Detroit United States of America 713,777
// Paris France 2,193,031
// New York City United States of America 8,175,133
//
// City Country Population
// Paris France 2,193,031
// Detroit United States of America 713,777
// New York City United States of America 8,175,133
// </Snippet1>
9 changes: 9 additions & 0 deletions samples/snippets/fsharp/VS_Snippets_CLR_System/system.comparison`1/fs/fs.fsproj
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<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net6.0</TargetFramework>
</PropertyGroup>
<ItemGroup>
<Compile Include="comparisont1.fs" />
</ItemGroup>
</Project>
2 changes: 2 additions & 0 deletions xml/System/Comparison`1.xml
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:::code language="cpp" source="~/samples/snippets/cpp/VS_Snippets_CLR/List`1_SortComparison/cpp/source.cpp" id="Snippet1":::
:::code language="csharp" source="~/samples/snippets/csharp/VS_Snippets_CLR/List`1_SortComparison/cs/source.cs" interactive="try-dotnet" id="Snippet1":::
:::code language="fsharp" source="~/samples/snippets/fsharp/VS_Snippets_CLR/List`1_SortComparison/fs/source.fs" id="Snippet1":::
:::code language="vb" source="~/samples/snippets/visualbasic/VS_Snippets_CLR/List`1_SortComparison/vb/source.vb" id="Snippet1":::

The following example uses the <xref:System.Comparison%601> delegate to sort the elements of a collection of `CityInfo` objects. `CityInfo` is an application-defined class that contains information about a city and its population. The example defines three methods, `CompareByName`, `CompareByPopulation`, and `CompareByNames`, that offer three different ways of ordering the `CityInfo` objects. Each method is assigned to the `comparison` argument of the <xref:System.Array.Sort%60%601%28%60%600%5B%5D%2CSystem.Comparison%7B%60%600%7D%29?displayProperty=nameWithType> method.

:::code language="csharp" source="~/samples/snippets/csharp/VS_Snippets_CLR_System/system.comparison`1/cs/comparisont1.cs" interactive="try-dotnet" id="Snippet1":::
:::code language="fsharp" source="~/samples/snippets/fsharp/VS_Snippets_CLR_System/system.comparison`1/fs/comparisont1.fs" id="Snippet1":::
:::code language="vb" source="~/samples/snippets/visualbasic/VS_Snippets_CLR_System/system.comparison`1/vb/comparisont1.vb" id="Snippet1":::

]]></format>
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