BinaryReader F# snippets (dotnet#8123)

Author: albert-du

snippets/fsharp/System.IO/BinaryReader/BaseStream/fs.fsproj

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

snippets/fsharp/System.IO/BinaryReader/BaseStream/rwdouble.fs

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+// <Snippet1>
+open System
+open System.IO
+
+let arrayLength = 1000
+
+// Create random data to write to the stream.
+let randomGenerator = Random()
+let dataArray = 
+    Array.init arrayLength (fun _ -> 100.1 * randomGenerator.NextDouble())
+do
+    use binWriter = new BinaryWriter(new MemoryStream())
+    // Write the data to the stream.
+    printfn $"Writing data to the stream."
+    for num in dataArray do
+        binWriter.Write num
+
+    // Create a reader using the stream from the writer.
+    use binReader = new BinaryReader(binWriter.BaseStream)
+    try
+        // Return to the beginning of the stream.
+        binReader.BaseStream.Position <- 0
+
+        // Read and verify the data.
+        printfn "Verifying the written data."
+        for num in dataArray do
+            if binReader.ReadDouble() <> num then
+                printfn "Error writing data."
+        printfn "The data was written and verified."
+    with :? EndOfStreamException as e ->
+        printfn $"Error writing data: {e.GetType().Name}."
+// </Snippet1>

snippets/fsharp/System.IO/BinaryReader/Overview/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" />
+    <Compile Include="source5.fs" />
+  </ItemGroup>
+</Project>

snippets/fsharp/System.IO/BinaryReader/Overview/source.fs

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+module source
+
+// <Snippet1>
+open System.IO
+open System.Text
+
+let fileName = "AppSettings.dat"
+
+let writeDefaultValues () =
+    use stream = File.Open(fileName, FileMode.Create)
+    use writer = new BinaryWriter(stream, Encoding.UTF8, false)
+    writer.Write 1.250F
+    writer.Write @"c:\Temp"
+    writer.Write 10
+    writer.Write true
+
+let displayValues () =
+    if File.Exists fileName then
+        use stream = File.Open(fileName, FileMode.Open)
+        use reader = new BinaryReader(stream, Encoding.UTF8, false)
+        let aspectRatio = reader.ReadSingle()
+        let tempDirectory = reader.ReadString()
+        let autoSaveTime = reader.ReadInt32()
+        let showStatusBar = reader.ReadBoolean()
+
+        printfn $"Aspect ratio set to: {aspectRatio}"
+        printfn $"Temp directory is: {tempDirectory}"
+        printfn $"Auto save time set to: {autoSaveTime}"
+        printfn $"Show status bar: {showStatusBar}"
+
+writeDefaultValues ()
+displayValues ()
+// </Snippet1>

snippets/fsharp/System.IO/BinaryReader/Overview/source5.fs

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+module source5
+
+//<snippet6>
+open System
+open System.IO
+open System.Text
+
+let CHUNK_SIZE = 1024
+
+let dumpBytes (bdata: byte[]) len =
+    let mutable j = 0
+    // 3 * 16 chars for hex display, 16 chars for text and 8 chars
+    // for the 'gutter' int the middle.
+    let dumptext = StringBuilder("        ", 16 * 4 + 8)
+    for i = 0 to len - 1 do
+        dumptext.Insert(j * 3, $"{int bdata[i]:X2} ") |> ignore
+        let dchar = char bdata[i]
+        //' replace 'non-printable' chars with a '.'.
+        let dchar = 
+            if Char.IsWhiteSpace dchar || Char.IsControl dchar then
+                '.'
+            else 
+                dchar
+        dumptext.Append dchar |> ignore
+        j <- j + 1
+        if j = 16 then
+            printfn $"{dumptext}"
+            dumptext.Length <- 0
+            dumptext.Append "        " |> ignore
+            j <- 0
+    // display the remaining line
+    if j > 0 then
+        for i = j to 15 do
+            dumptext.Insert(j * 3, "   ") |> ignore
+        printfn $"{dumptext}"
+
+[<EntryPoint>]
+let main args =
+    if args.Length = 0 || File.Exists args[0] |> not then
+        printfn "Please provide an existing file name."
+    else
+        use fs = new FileStream(args[0], FileMode.Open, FileAccess.Read)
+        use br = new BinaryReader(fs, ASCIIEncoding())
+        
+        let mutable chunk = br.ReadBytes CHUNK_SIZE
+        while chunk.Length > 0 do
+            dumpBytes chunk chunk.Length
+            chunk <- br.ReadBytes CHUNK_SIZE
+    0
+//</snippet6>

snippets/fsharp/System.IO/BinaryReader/Read/fs.fsproj

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

snippets/fsharp/System.IO/BinaryReader/Read/rwreadbytes.fs

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+module rwreadbytes
+
+// <Snippet1>
+open System
+open System.IO
+
+let arrayLength = 1000
+let dataArray = Array.zeroCreate<byte> arrayLength
+let verifyArray = Array.zeroCreate<byte> arrayLength
+
+Random().NextBytes dataArray
+
+do
+    use binWriter = new BinaryWriter(new MemoryStream())
+    printfn "Writing the data."
+    binWriter.Write(dataArray, 0, arrayLength)
+
+    use binReader = new BinaryReader(binWriter.BaseStream)
+    binReader.BaseStream.Position <- 0
+
+    if binReader.Read(verifyArray, 0, arrayLength) <> arrayLength then
+        printfn "Error writing the data."
+    else
+        for i = 0 to arrayLength - 1 do
+            if verifyArray[i] <> dataArray[i] then
+                printfn "Error writing the data."
+            else
+                printfn "The data was written and verified."
+// </Snippet1>

snippets/fsharp/System.IO/BinaryReader/Read/rwreadchar.fs

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+module rwreadchar
+
+// <Snippet1>
+open System
+open System.IO
+
+let invalidPathChars = Path.GetInvalidPathChars()
+let memStream = new MemoryStream()
+let binWriter = new BinaryWriter(memStream)
+
+// Write to memory.
+printf "Invalid file path characters are: "
+for i = 0 to invalidPathChars.Length - 1 do
+    binWriter.Write invalidPathChars[i]
+
+// Create the reader using the same MemoryStream
+// as used with the writer.
+let binReader = new BinaryReader(memStream)
+
+// Set Position to the beginning of the stream.
+memStream.Position <- 0
+
+// Read the data from memory and write it to the console.
+printf $"{binReader.ReadString()}"
+let memoryData =
+    [| for _ = 0L to memStream.Length - memStream.Position - 1L do
+        Convert.ToChar(binReader.Read()) |]
+printfn $"{memoryData}"
+// </Snippet1>

snippets/fsharp/System.IO/BinaryReader/Read/rwreadchars.fs

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+// <Snippet1>
+open System.IO
+
+let invalidPathChars = Path.GetInvalidPathChars()
+let memStream = new MemoryStream()
+let binWriter = new BinaryWriter(memStream)
+
+// Write to memory.
+binWriter.Write "Invalid file path characters are: "
+binWriter.Write(invalidPathChars, 0, invalidPathChars.Length)
+
+// Create the reader using the same MemoryStream
+// as used with the writer.
+let binReader = new BinaryReader(memStream)
+
+// Set Position to the beginning of the stream.
+memStream.Position <- 0
+
+// Read the data from memory and write it to the console.
+printf $"{binReader.ReadString()}"
+let arraySize = memStream.Length - memStream.Position |> int
+let memoryData = Array.zeroCreate<char> arraySize
+binReader.Read(memoryData, 0, arraySize) |> ignore
+printfn $"{memoryData}"
+// </Snippet1>

snippets/fsharp/System.IO/BinaryReader/ReadByte/fs.fsproj

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