How To Handle FileWrite's Trailing CRLFs?

S

Sir Isaac

Member
Probably, it is normal (from FileWrite's point of view) to append yet another crlf to the end of a string each time it saves it. A simple test demonstrates such behaviour (open "some.txt" in NotePad++, play Bonham's 'Moby Dick' on "Open" and "Save" buttons and see how the trail of crlfs grows):

B4X: 
Sub cmdOpen_Click
    ErrorLabel(errFO)
FileOpen(c1,"some.txt",cRead)
a = FileReadToEnd(c1)
FileClose(c1)
Return
   errFO:
   Msgbox("Can't open it, dude!")
End Sub

Sub cmdSave_Click
   ErrorLabel(errFS)
FileOpen(c1,"some.txt",cWrite)
FileWrite(c1,a)
FileClose(c1)
Return
   errFS:
   Msgbox("Can't save it, dude!")
End Sub

If my code is wrong, what's the right code? Else, what's the most elegant (resource-saving) technique to trim crlf (during or after each save)?

Insofar, my workaround is as follows:
B4X: 
If StrAt(a,StrLength(a)-2)=Chr(13) Then a=SubString(a,0,StrLength(a)-2)
This trims a string read from some.txt each time it is FileOpened. As a result, we always have only one extra crlf at the end of some.txt (no matter how many times the save button was fired).

Any other solutions (didn't find any on the forum yet)?
 
Last edited:
M

mjcoon

Well-Known Member
Licensed User
Sir Isaac said:
Any other solutions (didn't find any on the forum yet)?
Click to expand...

I think that the high-level answer is that FileWrite is a better match to FileRead because the latter just gives you the line content without new-line. So writing the same string with FileWrite puts back the new-line.

FileReadTo End does not match FileWrite so closely as you have discovered.

Mike.
 
S

Sir Isaac

Member
Saving with WriteBytes

Thanks, Erel, mjcoon,

WriteBytes's an interesting option. I believe it should work faster (shouldn't it?), and indeed, it doesn't add crlf:
B4X: 
Sub Globals
    Dim buffer(0) As Byte
    a=""
End Sub

Sub cmdOpen_Click
   ErrorLabel(errFO)
FileOpen(c1,"some.txt",cRead)
a = FileReadToEnd(c1)
FileClose(c1)
   Return
   errFO:
   Msgbox("Can't open it, dude!")
End Sub

Sub cmdSaveByte_Click
   ErrorLabel(errFSB)
FileOpen(c1,"some.txt",cRandom)
bin.New1(c1,False)
buffer()=bin.StringToBytes(a)
bin.WriteBytes(buffer())
FileClose(c1)
   Return
   errFSB:
   Msgbox("Can't save it, dude!")
End Sub

And finally, is it okay to combine a text method (FileReadToEnd) for opening file with a binary method (WriteBytes) for saving it? In particular, wouldn't the dynamic array of bytes (buffer()) create a memory overhead when saving a significant amount of text (as it doubles the same data, I suspect)?
 
Last edited:
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