Visual Basic Sequential File IO

Red Sunday

First off, I have found some articles on the MSDN website that have pointed me in the right direction but don't have all the answers. Also, I am using Visual Basic 6.0. I need to be able to access a file and do a couple of things with it: 1) I need to find out if it exists and if not, then create it. I found System.IO.File.Exists("c:\ExistingFileName") but I get an error. I believe this error is due to the fact that I have not told the compiler I am using the system namespace. How do you signal the compiler you are using the System namespace in Basic? In C it would be using System.IO.File, but I have no clue in Basic.:confused: 2) What is the command to create a sequential file in Basic and what variable will I have access to? 3) How do I add to it/ close it when I am done? Thank you, Zach Calvert ----------------- http://www.zachcalvert.com

Anonymous

here a sample http://www.andreavb.com/forum/news/viewtopic.php?TopicID=1485

Red Sunday

it doesn't use the system namespace. I am using this for a school project and I must use the system namespace. Also, it only reports error codes. I need to be able to check to see if it exists, not catch errors. ----------------- http://www.zachcalvert.com

Dave Kreskowiak

The System.IO namespace contains the File class. This class contains the shared .Exists method you use to check to see if the filename exists, prefferable using the FULL PATH to the file. .Exists isn't documented to throw any exceptions. It just returns True or False. In a normal installation of Visual Studio .NET or Visual Basic.NET, the System namespace is automatically imported into your project. You don't have to use the Imports System statement at the top of your code because it's already done behind the scenes. You DO, on the other hand, have to put in the Imports System.IO yourself, again, at the top of your code.

Imports System.IO

Public Class Form1
.
.
.
Private Sub WhatEver()
' You don't nedd to specify the System.IO namespace prefix because you
' already Imported it at the top of your code.
If File.Exists("C:\myTestFile.txt") Then
.
.
.

RageInTheMachine9532 "...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

Red Sunday

I'm using VB 6.0, and it doesn't let me do Imports System.IO What do I do now? ----------------- http://www.zachcalvert.com

Dave Kreskowiak

OK. Then throw out EVERYTHING about namespaces and System, System.IO, File.Exists... EVERYTHING. VB.NET is a VERY different language from VB6 and none of this stuff applies to VB6. Now, you'll have to use the FileSystemObject to see if the specified file exists. This will return either True or False, it doesn't throw any errors.

Set fs = CreateObject("Scripting.FileSystemObject")
If fs.FileExists("C:\\myTestFile.txt") Then
    .
    . ' The file exists...
    .
Else
    .
    . ' The file doesn't exist...
    .
End If

To open a text file for sequential write, you'll use the Open statement (docs here[^]):

Open "C:\\myTestFile.txt" For Output As #1
Print #1, "This is line 1"
Print #1, "This is line 2..."
Print #1, "This is line 3..."
Close #1

RageInTheMachine9532 "...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome