Computer Programming Concepts and Visual Basic David I. Schneider

The two-step procedure for reading data from a record is as follows:
1. Execute the statement
Get #n, r, recVar
to assign record r of file #n to the record variable recVar.
2. Use the field variables of the record variable to either display values with
picBox.Print or to transfer values to other variables with assignment statements.
EXAMPLE 2
The following program displays the entire contents of the random-access file COLLEGES.TXT.
‘In BAS Module
Public Type collegeData
nom As String * 30 ‘Name of college
state As String * 2 ‘State where college is located
yrFounded As Integer ‘Year college was founded
End Type
‘In Form code
Private Sub cmdDisplay_Click()
Call DisplayFile
End Sub
Private Sub DisplayFile()
Dim recordNum As Integer
‘Access the random-access file COLLEGES.TXT
Dim college As collegeData
Open “COLLEGES.TXT” For Random As #1 Len = Len(college)
picOutput.Cls
picOutput.Print “College”; Tab(30); “State”, Tab(45); “Year founded”
For recordNum = 1 To 3
Get #1, recordNum, college
picOutput.Print college.nom; Tab(30); college.state; _
Tab(45); college.yrFounded
Next recordNum
Close #1
End Sub
[Run, and click the command button.]
The total number of characters in the file with reference number n is given by the value
of the function
LOF(n)
The number of the last record in the file can be calculated by dividing this value by the record
length. The LOF function, rather than the EOF function, should be used to determine when the
end of the file has been reached. For instance, in Example 2, the For statement in the Sub procedure
DisplayFile can be written as
Random-Access Files 253