read the first 5 characters of file

S-Soft 646 Reputation points
2022-11-13T19:23:43.683+00:00

hi,
user might select any file type, with or without extension, need to get the 5 characters of file without opening and reading the whole file, like ReadAllText
help please :)

VB
VB
An object-oriented programming language developed by Microsoft that is implemented on the .NET Framework. Previously known as Visual Basic .NET.
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  1. Viorel 114.4K Reputation points
    2022-11-13T19:58:58.733+00:00

    Try something like this:

    Dim characters(4) As Char  
      
    Using f = File.OpenText("C:\MyFile.txt")  
        f.Read(characters, 0, 5)  
    End Using  
    
    Dim text As String = String.Concat(characters).TrimEnd(Chr(0))  
    
    1 person found this answer helpful.

  2. WayneAKing 4,921 Reputation points
    2022-11-14T00:28:03.427+00:00

    user might select any file type, with or without extension,
    need to get the 5 characters of file

    It may depend on what you mean by "characters".

    Do you mean one byte, as in a raw file dump?

    Or do you really mean characters, such as 5 ASCII characters or
    5 Unicode characters, etc.

    For getting the first 5 bytes from any file, including binary
    types such as .exe, .dll, etc. try this code.

    NOTE: For brevity I have omitted all error checks. For robust
    code you will need to add them. Such as file open failures,
    files less than 5 bytes long, etc.

    For testing in the IDE, the file test.exe will need to be in
    the same folder as the program's .exe - such as ..\bin\debug

    Imports System.IO  
    Module Module1  
      
        Sub Main()  
            Dim bArray(4) As Byte  
            Dim filename As String = "test.exe"  
            Dim stream = File.Open(filename, FileMode.Open)  
            Dim reader = New BinaryReader(stream)  
            For index = 0 To 4  
                bArray(index) = reader.ReadByte  
            Next  
            For index = 0 To 4  
                Console.WriteLine("{0:X2}", bArray(index))  
            Next  
        End Sub  
      
    End Module  
      
    
    • Wayne
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  3. WayneAKing 4,921 Reputation points
    2022-11-14T00:39:53.707+00:00

    In my last example, note that the for loop to get the bytes
    can be replaced with a ReadBytes(5) instruction:

    'For index = 0 To 4  
    '    bArray(index) = reader.ReadByte  
    'Next  
    bArray = reader.ReadBytes(5)  
      
    
    • Wayne
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