Reading from files using readdir and nextfile

Archives Forums/BlitzMax Bug Reports/Reading from files using readdir and nextfile

MadJack

(Posted 2011) [#1]

As a Bmax noob I've probably made an error here, but I'm getting strange behavior when using ReadDir/NextFile to read data from a series of text files.

Nextfile sucessfully gives the next filename and FILE_STREAM appears to open the file for reading, but Eof(FILE_STREAM) is reached immediately, so no data is read.

Only if I add the full path to the filename will it allow me to read the data e.g. FILE_NAME = CDIR + "DATA/" + FILE_NAME

(running W7 64)

	Strict
	
	Global CDIR:String; ChangeDir("..") ; CDIR = CurrentDir()
	If Right(CDIR, 1) <> "/" Then CDIR = CDIR + "/"
	
	Local FLAG_CFG
	Local FOLDER_DATA:int = ReadDir(CDIR + "DATA")
	Local FILE_NAME:String
	Local FILE_STREAM:TStream
	Local DATA_LINE:String
		 
	Repeat
		FLAG_CFG = 0
		FILE_NAME = NextFile(FOLDER_DATA)
		If FILE_NAME <> "" Then FLAG_CFG = 1
		              'FILE_NAME = CDIR + "DATA/" + FILE_NAME - uncomment to have file not eof immediately 
		If Instr(Upper(FILE_NAME), ".CFG") Then			 
		    FILE_STREAM = ReadFile(FILE_NAME)
		    If FILE_STREAM <> Null
		    	 While Not Eof(FILE_STREAM)
				 Print ReadLine(FILE_STREAM)
			Wend
			CloseStream FILE_STREAM
			End If
		EndIf		
	Until FLAG_CFG = 0
	
	CloseDir FOLDER_DATA

Last edited 2011

Last edited 2011

mpmxyz

(Posted 2011) [#2]

I think you have done a mistake:

ReadDir(CDIR + "DATA")

->You go through "currentdir/DATA/*".

FILE_NAME = NextFile(FOLDER_DATA)
FILE_STREAM = ReadFile(FILE_NAME)

->You read from "currentdir/*" because "NextFile" returns a filename but not a full path.
One question before you fix your code:
Is "FILE_STREAM <> Null" 'true'?
If it is something else went wrong.
PS: You can use "ExtractExt" to check the filename extension easier.

MadJack

(Posted 2011) [#3]

mpmxyz

That's what threw me - FILE_STREAM does not return a null after ReadFile(FILE_NAME) and so I assumed it had sucessfully opened the file.

(thanks for the ext check tip)

Last edited 2011

mpmxyz

(Posted 2011) [#4]

When I tested your code, ReadFile only returned Null.

Strict

Global CDIR:String; ChangeDir("..") ; CDIR = CurrentDir()
If Right(CDIR, 1) <> "/" Then CDIR = CDIR + "/"

Local FLAG_CFG
Local FOLDER_DATA:Int = ReadDir(CDIR + "DATA")
DebugLog CDIR + "DATA"
Local FILE_NAME:String
Local FILE_STREAM:TStream
Local DATA_LINE:String
	 
Repeat
	FLAG_CFG = 0
	FILE_NAME = NextFile(FOLDER_DATA)
	If FILE_NAME <> "" Then FLAG_CFG = 1
	'FILE_NAME = CDIR + "DATA/" + FILE_NAME - uncomment to have file not eof immediately 
	If Instr(Upper(FILE_NAME), ".CFG") Then			 
		FILE_STREAM = ReadFile(FILE_NAME)
		DebugLog "found "+FILE_NAME
		If FILE_STREAM <> Null
			DebugLog "read "+FILE_NAME
			While Not Eof(FILE_STREAM)
				Print ReadLine(FILE_STREAM)
			Wend
			CloseStream FILE_STREAM
		End If
	EndIf		
Until FLAG_CFG = 0

CloseDir FOLDER_DATA

What is written via DebugLog?
PS: There are a lot useful functions in brl.FileSystem. (e.g. StripSlash)