Question

I try to learn F# and at this time i try to convert a simple C# Function to F#
in some points i stuck at example var compressedData = new byte[memoryStream.Length]; < C#
here the full c# function

public static string CompressString(string text)
{
    byte[] buffer = Encoding.UTF8.GetBytes(text);
    var memoryStream = new MemoryStream();
    using (var gZipStream = new GZipStream(memoryStream, CompressionMode.Compress, true))
    {
        gZipStream.Write(buffer, 0, buffer.Length);
    }

    memoryStream.Position = 0;

    var compressedData = new byte[memoryStream.Length];
    memoryStream.Read(compressedData, 0, compressedData.Length);

    var gZipBuffer = new byte[compressedData.Length + 4];
    Buffer.BlockCopy(compressedData, 0, gZipBuffer, 4, compressedData.Length);
    Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, gZipBuffer, 0, 4);
    return Convert.ToBase64String(gZipBuffer);
}

and here Mine half Translated version

let compress(text:string)=
    let buffer = Encoding.UTF8.GetBytes(text)
    use memoryStream = new MemoryStream()
    let gZipStream = new GZipStream(memoryStream, CompressionMode.Compress, true)
    gZipStream.Write(buffer, 0, buffer.Length)
    memoryStream.Position <- Convert.ToInt64(0)
    let compressedData = Array.init memoryStream.Length(fun i -> byte) //< Here i stuck
    memoryStream.Read(compressedData, 0, compressedData.Length)
    use gZipBuffer = (compressedData.Length + 4)

the last three days i have searched on google to solve my problem, but i didnt find any solution.
I hope someone here can help me 🙂
Thank you very much in advance

Answer 1

You’re looking for Array.zeroCreate.

let compressedData = Array.zeroCreate (int memoryStream.Length)