Android Question [SOLVED]writing txt

Hi,

Please i need hellp on modify a existing txt but i only want to change one line.

example:

Code:

1
2
3
4

or

1,2,3,4

I want to replace the third position to A and leave the others without any change

Code:

1
2
A
4

or

1,2,A,4

Its is possible?

Thanks

 

MyText=Mytext.Replace("3", "A")

Take a look at string functions of B4A

 

If you don't know the value of the 3rd entry, you can use Regex.Split:

Code:

Sub FieldReplace(FieldNo As Int,Delim As String,Source As String,ReplacementStr As String) As String

    'Stops arrayindex out of bounds error
    If FieldNo < 0 Then Return Source

    Dim T() As String = Regex.Split(Delim,Source)

    'Stops arrayindex out of bounds error
    If FieldNo >= T.Length Then Return Source

    T(FieldNo) = ReplacementStr

    'Build Return String
    Dim ReturnStr As String
    For i = 0 To T.Length - 1
        ReturnStr =  ReturnStr & T(i)
        If i < T.Length - 1 Then ReturnStr = ReturnStr & Delim
    Next
    Return ReturnStr
End Sub

Use As:

Code:

Dim Str As String = "1,2,3,4"
    Log(FieldReplace(2,",",Str,"A")) 'Positions are zero based same as arrays

 

Ok, now how can i save the replace "field" to txt (only the modify and keep the others)?

Special thanks to @KMatle and @stevel05

 

Code:

Sub GetField(FieldNo As Int,Delim As String,Source As String) As String
    'Stops arrayindex out of bounds error
    If FieldNo < 0 Then Return ""
   
    Dim T() As String = Regex.Split(Delim,Source)
   
    'Stops arrayindex out of bounds error
    If FieldNo >= T.Length Then Return ""
   
    Return T(FieldNo)
End Sub

Usage:

Code:

Dim Str As String = "1,2,3,4"
    Dim TexttoReplace As String = GetField(2,",",Str)
    Log(FieldReplace(2,",",Str,"A"))

 

This write the update txt to device?

 

No, it will be in the variable TexttoReplace. you can use TextWriter: http://www.b4x.com/android/help/files.html#textwriter to save it to a file.

 

I suggest starting at the Beginners Guide and then working trhrough it and all it´s samples to get further. The start at the users guide (all examples here too) then.

It should dont need this thread knowing the basics!

 

exactly!

 

Code:

Sub bt_1_Click
    Dim xx As String
    xx = 1
    Stre  = Items(0) & "," &  Items(1) &  "," & xx  & "," &  Items(3)
    File.WriteString(File.DirRootExternal, "TT.txt", _
        Stre)
End Sub

Thanks @stevel05

@Manfred i dont now why every time you reply to my posts you have to implicate...

Code:

http://www.b4x.com/android/forum/threads/solved-tts-service-for-2-activitys.49877/#post-311439

 

He is not implicating... but there are noob questions... and then there are the "I don't care about the search engine on the top right of the this site" questions...
yours are more on the later category...

 

I dont wont to start any problems i just fell what i write just that... Thanks