C#•2y ago

✅ How to terminate reading a set of string chars when a null character is detected.

I have a video file custom made by my company which from the start of the file and a few bytes after that, has a set of strings (a name in my case which contains the name of the person that has encoded the video). I have attached a example image of how a name typically looks from a hex editor. What I am doing is making an app that would get the name from these bytes and display it in a textbox. I am running into some problems here in doing so. Using StreamReader to read data from a file other than a text file is generally not recommended and so I decided to use binary reader. the problem with binary reader is that you have to specify the amount of chars to read when using the .ReadChars() method. Since names cannot always be the same fixed length, you would have to end it on seeing a null character and here in this image, the encoder name's set of bytes that I have highlighted ends with a null character. Here is the current code that I am using:

br.BaseStream.Position = EncoderNamePos;
var GetEncoderName = br.ReadChars(13);
var EncoderName = string.Join("", GetEncoderName);

br.BaseStream.Position = EncoderNamePos;
var GetEncoderName = br.ReadChars(13);
var EncoderName = string.Join("", GetEncoderName);

How do I handle this problem ? is there a way by which I can end reading as soon as the null character is read in binary reader?

14 Replies

MODiX•2y ago

❯ Method: System.IO.BinaryReader.ReadString() Reads a string from the current stream. The string is prefixed with the length, encoded as an integer seven bits at a time.

React with ❌ to remove this embed.

ero•2y ago

bogus make an extension method i guess

static class BinaryReaderExt
{
  public static string? ReadStringNullTerminated(this BinaryReader br)
  {
    StringBuilder sb = new();

    char c;
    while ((c = br.ReadChar()) != default)
    {
      sb.Append(c);
    }

    return sb.ToString();
  }
}

static class BinaryReaderExt
{
  public static string? ReadStringNullTerminated(this BinaryReader br)
  {
    StringBuilder sb = new();

    char c;
    while ((c = br.ReadChar()) != default)
    {
      sb.Append(c);
    }

    return sb.ToString();
  }
}

Surihia•2y ago

umm..where exactly is it specifying to terminate at a null character ?

ero•2y ago

(c = br.ReadChar()) != default

Surihia•2y ago

ero•2y ago

replace default with '\0' if you want or (char)0

Surihia•2y ago

Do I have to implement it as you have shown ? I thought I can input a normal code lines as I am not familiar with using methods like that.

ero•2y ago

it would be preferrable to implement it like that there's nothing more to do than copy and paste it (preferrably in its own file) and then just use br.ReadStringNullTerminated()

Surihia•2y ago

do I have to use a separate namespace for this ? I get an error stating that target-typed object creation is not available in C# 7.3.

ero•2y ago

so don't use it... StringBuilder sb = new StringBuilder(); put it in any namespace you feel like

Surihia•2y ago

should I include the ? after public static string. I get an error if I put the ? there.

ero•2y ago

you don't get an error you get a warning since you're using framework, no, don't include it and upgrade your framework

Surihia•2y ago

Well I managed to implement it without a method and its all good now Thanks for the help as usual 🙂

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity. Closed!

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✅ How to terminate reading a set of string chars when a null character is detected.