Saving and restoring data to a text file (with a twist)

VB400 · Oct 20, 1999

I have the need to write a single string to a text file and later retrieve that text into a variable -- sounds simple, but... 
I can do this with simple code using "open", "print #" and "close" followed by "open", "input #" and "close". This works well depending on the data that is in the string variable. 
 
In my case, the string is a representation of a propertybag's contents. When I write the string to the text file, it includes various characters that are generated by propertybag. When I read the text file into a string variable, I lose some of those characters (mainly the chr(0) character). Here's a simple application that you can copy into a module and run to see what I'm talking about (change the project startup to Sub Main): 
 
Sub main() 
 
Dim pb As PropertyBag 
Dim s As String 
 
Set pb = New PropertyBag 
pb.WriteProperty "Item", "ABCDEFG" 
s = pb.Contents 
Set pb = Nothing 
 
'Output to text file 
Open "c:\testing.txt" For Output As #1 
Print #1, s 
Close #1 
Debug.Print s 
 
'Input from text file 
s = "" 
Open "c:\testing.txt" For Input As #1 
Line Input #1, s 
Debug.Print s 
Close #1 
 
End Sub 
 
The result is this (notice how the blanks are gone -- they're actually chr(0)s not blanks): 
? 0 ?? item ABCDEFG 
?0??itemABCDEFG 
 
Any Ideas?

Logit · Nov 1, 1999

I made the following changes to your code, placing same into 
a Command Button to click on. The program runs fine for 
me without any errors. Will this modification work for you ? 
 
Jim - <A HREF="mailto:jdmcjen@stc.net">jdmcjen@stc.net</A> 
 
Private Sub Command1_Click() 
'Dim pb As PropertyBag 
Dim s As String 
 
'Set pb = New PropertyBag 
'pb.WriteProperty "Item", "ABCDEFG" 
s = "ABCDEFG" 'pb.Contents 
'Set pb = Nothing 
 
'Output to text file 
Open "c:\testing.txt" For Output As #1 
Print #1, s 
Close #1 
Debug.Print s 
 
'Input from text file 
s = "" 
Open "c:\testing.txt" For Input As #1 
Line Input #1, s 
Debug.Print s 
Close #1 
End Sub

VB400 · Nov 4, 1999

Thanks Logit 
 
The modification you made works for strings. Im my case, the data to be saved is originated by 
PropertyBag.Contents which is a byte array not a string.

johncb · Nov 8, 1999

A couple of suggestions: 
1. Open the file for BINARY and see if that makes a difference. 
 
2. Traverse the string 's' and replace each occurrence of chr(0) with say "CHRZERO" then write the file. When you read the string in you change "CHRZERO" back to chr(0). 
e.g. 
 
dim tempS as string, i as integer 
for i = 1 to len( s) 
if mid(s, i, 1) = chr(0) then 
tempS = tempS & "CHRZERO" 
else 
tempS = mid(s, i, 1) 
next i 
Print #1, tempS 
 
Do the reverse when you read the string back. 
You can then include this solution for any character that gives you a problem. 
 
NOTE: i have not tested this code. It looks ok but it may have bugs. 
 
HTH 
johncb

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Saving and restoring data to a text file (with a twist)

VB400

Programmer

Logit

Programmer

VB400

Programmer

johncb

Programmer

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