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Reading/Writing files

Blitz3D Forums/Blitz3D Beginners Area/Reading/Writing files

_PJ_(Posted 2004) [#1]
I wish to include a log file for my game - which will recird chat messages/system notes etc.

I had assumed it's not a good idea to keep the stream open ALL the time, so it will be opened, written to, then closed again each time.

This causes a problem if I need to add consecutive lines later, as each time I open it, the 'pointer' moves to the start of the file.

The immediate workaround I thought of was to read the contents each time, then re-write. Thjis of course, would take too long with large logs and defeat the object of having the file...

Is there a simple way to 'move' to the EOF?

here's my trial code:

Graphics3D 800,600,32

;CLEAR LOG FOR NEW GAME
debug=OpenFile ("Log.log")
While Not Eof (debug)
WriteLine debug,""
Wend

WriteLine debug,"START OF LOG"
CloseFile debug

;LATER ON - CONSECUTIVE LINE

sphere=CreateSphere(10)

debug=OpenFile ("Log.log")
WriteLine debug,"Created Sphere"
CloseFile debug



Kev(Posted 2004) [#2]
checkout SeekFile() for checking position in the file. and Eof() for checking the end of the file.


semar(Posted 2004) [#3]
@Malice,
if you need to append text to a file, why don't you use the file stream commands ?

http://www.blitzbasic.com/bpdocs/command.php?name=WriteLine&ref=2d_cat

In this way, each time you open a file and write a line on it, the line will be appended at the end of the file, thus the previous file content will be preserved.

Hope this helps,
Sergio.


_PJ_(Posted 2004) [#4]
semar - Providin I unbderstand you correctly... that's what Ive tried!
I had assumed it's not a good idea to keep the stream open ALL the time, so it will be opened, written to, then closed again each time.



Kev, I looked at FilePos & SeekFile but neither seemed to describe how to move the position.


aCiD2(Posted 2004) [#5]
what you need to do is, SeekFile(stream, EOF(samestream)). That way the pointer is at the end of the file, dont try to read anything though ^_^


_PJ_(Posted 2004) [#6]
Great thanks!


gameshastra(Posted 2007) [#7]
Is there any funciton to append data to a file. For example i am drawing a line and i could like to store those x and y values in a file. If i use WriteLine function i can able to get the last x and y values. I think its overwriting the old values. So is there any file modes like "Append" mode to open a file and append the data?


b32(Posted 2007) [#8]
Yes, you should open the file with OpenFile, and then seek to the end of the file using SeekFile:
fname$ = "test2.dat"

SeedRnd(MilliSecs())

;test if file exists
test = FileType(fname$)

;if it doesn't
If Not test Then
		
	;createfile
	file = WriteFile(fname$)

;if it does		
Else
	
	;open file
	file = OpenFile(fname$)
	;seek to end of file
	SeekFile file, FileSize(fname$)
	
End If

;add line and close file
WriteLine file, "testline " + Rand(255) 
CloseFile file

;print file
file  = ReadFile(fname$)
While Not(Eof(file))

	Print ReadLine(file)
	
Wend
CloseFile file

WaitKey()
End