Explaining text files

[pliroforikos]

Today i'm playing with files but i have a question maybe someone can help.

File.OpenOutput (Dir As String, FileName As String, Append As Boolean)
- Opens the given file for output, the Append parameter tells whether the text will be added at the
end of the existing file or not. If the file doesn't exist it will be created.

Acording File.OpenOutput if i set Append to True i will add new data at the end of the file

but the code bellow deletes the previous data

File.OpenOutput(strFolder, fn, True)
    
Private msg As String = "Hello World 2"
File.WriteString(strFolder, fn, msg)
    
Private msg As String = "Hello World 3"
File.WriteString(strFolder, fn, msg)

In booklets i'm reading

File.WriteString (Dir As String, FileName As String, Text As String)
- Writes the given text to a new file.

So it creates a new file with same name? And what about appending?

Thank you all

 

[ilan]

File.writestring() will create a new file (if it doesnot already exists) and if it exists it will overwrite the existing file.

if you want to append any data to a file you can use outputstream like this:

    Dim txt As String = "test "
    Dim bytes() As Byte = txt.GetBytes("UTF8")
    Dim out As OutputStream = File.OpenOutput(File.DirApp, "test.txt", True)
    out.WriteBytes(bytes,0,bytes.Length)
    out.Close

you will need to convert the data to bytes to save the data but like this you can append data to data that is already existing.

 

[pliroforikos]

File.writestring() will create a new file (if it doesnot already exists) and if it exists it will overwrite the existing file.

if you want to append any data to a file you can use outputstream like this:

    Dim txt As String = "test "
    Dim bytes() As Byte = txt.GetBytes("UTF8")
    Dim out As OutputStream = File.OpenOutput(File.DirApp, "test.txt", True)
    out.WriteBytes(bytes,0,bytes.Length)
    out.Close

you will need to convert the data to bytes to safe the data but like this you can append data to data that is already existing.

Thank you,
something without converting to bytes?

 

[ilan]

Thank you,
something without converting to bytes?

maybe something like this:

    File.WriteString(File.DirApp,"test.txt","this is the first line")
   
    '....'
   
    Dim sb As StringBuilder
    sb.Initialize
    sb.Append(File.ReadString(File.DirApp,"test.txt")).Append(CRLF).Append("this is the second line")
    File.WriteString(File.DirApp,"test.txt",sb.ToString)

 

[pliroforikos]

Thank you again
I'm looking for a solution that it will be easy to explain to young students that they are dealing with files for a first time.
And all time i have to do is about 90 - 130 minutes. In this time i have to explain everything about text files, adding text, list and maps making new folders and do some examples and give them some exercises.

 

[ilan]

Thank you again
I'm looking for a solution that it will be easy to explain to young students that they are dealing with files for a first time.
And all time i have to do is about 90 - 130 minutes. In this time i have to explain everything about text files, adding text, list and maps making new folders and do some examples and give them some exercises.

Good Luck

 

[Erel]

Another option is to use TextWriter:

Dim out As OutputStream = File.OpenOutput(xui.DefaultFolder, "test.txt", True)
Dim tw As TextWriter
tw.Initialize(out)
tw.WriteLine("hello")
tw.WriteLine("good bye")
tw.Close

Note that writing to File.DirApp involves an assumption that it is possible to write to the program folder. In many cases it will not possible as the program will be inside Program Files, which is a restricted folder.

It is safer to use xui.DefaultFolder = File.DirData.