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IntPtr F# snippets (#7754)
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16 files changed

+326
-4
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‎snippets/fsharp/System/IntPtr/Add/add1.fs‎

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// <Snippet1>
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#nowarn "9"
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open System
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open System.Runtime.InteropServices
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open FSharp.NativeInterop
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[<EntryPoint>]
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let main _ =
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let mutable arr =
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[| 2; 4; 6; 8; 10; 12; 14; 16; 18; 20 |]
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use parr = fixed arr
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let ptr = NativePtr.toNativeInt parr
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// Get the size of an array element.
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let size = sizeof<int>
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for i = 0 to arr.Length - 1 do
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let newPtr = IntPtr.Add(ptr, i * size)
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printf $"{Marshal.ReadInt32 newPtr} "
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0
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// The example displays the following output:
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// 2 4 6 8 10 12 14 16 18 20
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// </Snippet1>

‎snippets/fsharp/System/IntPtr/Add/fs.fsproj‎

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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>net6.0</TargetFramework>
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</PropertyGroup>
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<ItemGroup>
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<Compile Include="add1.fs" />
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</ItemGroup>
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</Project>

‎snippets/fsharp/System/IntPtr/Overview/fs.fsproj‎

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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>net6.0</TargetFramework>
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</PropertyGroup>
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<ItemGroup>
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<Compile Include="topointer.fs" />
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</ItemGroup>
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</Project>

‎snippets/fsharp/System/IntPtr/Overview/topointer.fs‎

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//<snippet1>
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#nowarn "9"
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open System.Runtime.InteropServices
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open FSharp.NativeInterop
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[<EntryPoint>]
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let main _ =
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let stringA = "I seem to be turned around!"
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let mutable copylen = stringA.Length
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// Allocate HGlobal memory for source and destination strings
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let sptr = Marshal.StringToHGlobalAnsi stringA
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let dptr = Marshal.AllocHGlobal(copylen + 1)
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let mutable src: byte nativeptr = sptr.ToPointer() |> NativePtr.ofVoidPtr
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let mutable dst: byte nativeptr = dptr.ToPointer() |> NativePtr.ofVoidPtr
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if copylen > 0 then
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// set the source pointer to the end of the string
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// to do a reverse copy.
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src <-
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NativePtr.toNativeInt src + nativeint (copylen - 1)
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|> NativePtr.ofNativeInt
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while copylen > 0 do
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copylen <- copylen - 1
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NativePtr.read src |> NativePtr.write dst
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dst <- NativePtr.toNativeInt dst + 1n |> NativePtr.ofNativeInt
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src <- NativePtr.toNativeInt src - 1n |> NativePtr.ofNativeInt
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NativePtr.write dst 0uy
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let stringB = Marshal.PtrToStringAnsi dptr
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printfn $"Original:\n{stringA}\n"
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printfn $"Reversed:\n{stringB}"
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// Free HGlobal memory
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Marshal.FreeHGlobal dptr
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Marshal.FreeHGlobal sptr
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0
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// The progam has the following output:
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//
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// Original:
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// I seem to be turned around!
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//
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// Reversed:
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// !dnuora denrut eb ot mees I
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//</snippet1>

‎snippets/fsharp/System/IntPtr/Subtract/fs.fsproj‎

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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>net6.0</TargetFramework>
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</PropertyGroup>
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<ItemGroup>
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<Compile Include="subtract1.fs" />
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</ItemGroup>
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</Project>

‎snippets/fsharp/System/IntPtr/Subtract/subtract1.fs‎

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// <Snippet1>
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#nowarn "9"
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open System
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open System.Runtime.InteropServices
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open FSharp.NativeInterop
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[<EntryPoint>]
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let main _ =
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let arr =
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[| 2; 4; 6; 8; 10; 12; 14; 16; 18; 20 |]
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// Get the size of a single array element.
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let size = sizeof<int>
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use pend = fixed &arr[arr.GetUpperBound 0]
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let ptr = NativePtr.toNativeInt pend
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for i = 0 to arr.Length - 1 do
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let newPtr = IntPtr.Subtract(ptr, i * size)
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printf $"{Marshal.ReadInt32 newPtr} "
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0
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// The example displays the following output:
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// 20 18 16 14 12 10 8 6 4 2
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// </Snippet1>

‎snippets/fsharp/System/IntPtr/ToPointer/fs.fsproj‎

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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>net6.0</TargetFramework>
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</PropertyGroup>
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<ItemGroup>
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<Compile Include="topointer.fs" />
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</ItemGroup>
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</Project>

‎snippets/fsharp/System/IntPtr/ToPointer/topointer.fs‎

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//<snippet1>
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#nowarn "9"
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open System.Runtime.InteropServices
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open FSharp.NativeInterop
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[<EntryPoint>]
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let main _ =
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let stringA = "I seem to be turned around!"
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let mutable copylen = stringA.Length
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// Allocate HGlobal memory for source and destination strings
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let sptr = Marshal.StringToHGlobalAnsi stringA
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let dptr = Marshal.AllocHGlobal(copylen + 1)
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let mutable src: byte nativeptr = sptr.ToPointer() |> NativePtr.ofVoidPtr
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let mutable dst: byte nativeptr = dptr.ToPointer() |> NativePtr.ofVoidPtr
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if copylen > 0 then
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// set the source pointer to the end of the string
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// to do a reverse copy.
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src <-
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NativePtr.toNativeInt src + nativeint (copylen - 1)
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|> NativePtr.ofNativeInt
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while copylen > 0 do
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copylen <- copylen - 1
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NativePtr.read src |> NativePtr.write dst
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dst <- NativePtr.toNativeInt dst + 1n |> NativePtr.ofNativeInt
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src <- NativePtr.toNativeInt src - 1n |> NativePtr.ofNativeInt
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NativePtr.write dst 0uy
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let stringB = Marshal.PtrToStringAnsi dptr
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printfn $"Original:\n{stringA}\n"
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printfn $"Reversed:\n{stringB}"
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// Free HGlobal memory
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Marshal.FreeHGlobal dptr
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Marshal.FreeHGlobal sptr
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0
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// The progam has the following output:
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//
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// Original:
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// I seem to be turned around!
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//
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// Reversed:
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// !dnuora denrut eb ot mees I
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//</snippet1>

‎snippets/fsharp/System/IntPtr/Zero/fs.fsproj‎

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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>net6.0</TargetFramework>
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</PropertyGroup>
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<ItemGroup>
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<Compile Include="zero2.fs" />
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<Compile Include="zero4.fs" />
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</ItemGroup>
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</Project>

‎snippets/fsharp/System/IntPtr/Zero/zero2.fs‎

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module zero2
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// <Snippet1>
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open System
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open System.Runtime.InteropServices
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let GW_OWNER = 4
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[<DllImport("user32", CharSet=CharSet.Auto, SetLastError=true, ExactSpelling=true)>]
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extern IntPtr GetWindow(nativeint hwnd, int wFlag)
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let hwnd = IntPtr 3
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let hOwner = GetWindow(hwnd, GW_OWNER)
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if hOwner = IntPtr.Zero then
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printfn "Window not found."
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// The example displays the following output:
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// Window not found.
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// </Snippet1>

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