byte[] array = Encoding.ASCII.GetBytes("MyTest1 - MyTest2");
MemoryStream streamItem = new MemoryStream(array);

// convert to string
StreamReader reader = new StreamReader(streamItem);
string text = reader.ReadToEnd();

使用StreamReader，然后你可以使用ReadToEnd方法返回一个字符串。

你也可以使用

Encoding.ASCII.GetString(ms.ToArray());

我不认为这是低效率，但我不能保证。它还允许您选择不同的编码，而使用StreamReader时，您必须将其指定为参数。

为什么不在MemoryStream类型上做一个很好的扩展方法呢?

public static class MemoryStreamExtensions
{

    static object streamLock = new object();

    public static void WriteLine(this MemoryStream stream, string text, bool flush)
    {
        byte[] bytes = Encoding.UTF8.GetBytes(text + Environment.NewLine);
        lock (streamLock)
        {
            stream.Write(bytes, 0, bytes.Length);
            if (flush)
            {
                stream.Flush();
            }
        }
    }

    public static void WriteLine(this MemoryStream stream, string formatString, bool flush, params string[] strings)
    {
        byte[] bytes = Encoding.UTF8.GetBytes(String.Format(formatString, strings) + Environment.NewLine);
        lock (streamLock)
        {
            stream.Write(bytes, 0, bytes.Length);
            if (flush)
            {
                stream.Flush();
            }
        }
    }

    public static void WriteToConsole(this MemoryStream stream)
    {
        lock (streamLock)
        {
            long temporary = stream.Position;
            stream.Position = 0;
            using (StreamReader reader = new StreamReader(stream, Encoding.UTF8, false, 0x1000, true))
            {
                string text = reader.ReadToEnd();
                if (!String.IsNullOrEmpty(text))
                {
                    Console.WriteLine(text);
                }
            }
            stream.Position = temporary;
        }
    }
}

当然，在将这些方法与标准方法结合使用时要小心。:)……为了实现并发性，你需要使用那个方便的streamLock。

使用StreamReader将MemoryStream转换为字符串。

<Extension()> _
Public Function ReadAll(ByVal memStream As MemoryStream) As String
    ' Reset the stream otherwise you will just get an empty string.
    ' Remember the position so we can restore it later.
    Dim pos = memStream.Position
    memStream.Position = 0

    Dim reader As New StreamReader(memStream)
    Dim str = reader.ReadToEnd()

    ' Reset the position so that subsequent writes are correct.
    memStream.Position = pos

    Return str
End Function

稍微修改了Brian的答案，允许可选的读启动管理，这似乎是最简单的方法。可能不是最有效的，但容易理解和使用。

Public Function ReadAll(ByVal memStream As MemoryStream, Optional ByVal startPos As Integer = 0) As String
    ' reset the stream or we'll get an empty string returned
    ' remember the position so we can restore it later
    Dim Pos = memStream.Position
    memStream.Position = startPos

    Dim reader As New StreamReader(memStream)
    Dim str = reader.ReadToEnd()

    ' reset the position so that subsequent writes are correct
    memStream.Position = Pos

    Return str
End Function