Computer Programming Concepts and Visual Basic David I. Schneider

56 Computer Programming Concepts and Visual Basic
sends expr to the printer in exactly the same way picBox.Print sends output to a picture box.
You can use semicolons, commas for print zones, and Tab.
Font properties can be set with statements like
Printer.Font.Name = “Script”
Printer.Font.Bold = True
Printer.Font.Size = 12
Another useful printer command is
Printer.NewPage
which starts a new page.
Windows’ print manager usually waits until an entire page has been completed before
starting to print. To avoid losing information, execute the statement
Printer.EndDoc
when you are finished printing.
The statement
PrintForm
prints the content of the form.
■ INTERNAL DOCUMENTATION
Now that we have the capability to write more complicated programs, we must concern ourselves
with program documentation. Program documentation is the inclusion of comments
that specify the intent of the program, the purpose of the variables, the nature of the data in
the files, and the tasks performed by individual portions of the program. To create a comment
line, just begin the line with an apostrophe. Such a line is completely ignored when the program
is executed. (The keyword Rem can be used instead of an apostrophe. Rem is an abbreviation
of Remark.) Program documentation appears whenever the program is displayed or
printed. Also, a line of code can be documented by adding an apostrophe, followed by the desired
information, to the end of the line. Comments (also known as Rem statements) appear
green on the screen.
EXAMPLE 7
Document the program in Example 2.
SOLUTION
In the following program, the first comment describes the entire program, the next three comments give
the meanings of the variables, and the final comment describes the items in each line of the file.
Private Sub cmdCompute_Click()
‘Compute weekly pay
Dim nom As String ‘Employee name
Dim wage As Single ‘Hourly pay
Dim hrs As Single ‘Number of hours worked during week
picPay.Cls
Open “STAFF.TXT” For Input As #1
‘Get person’s name, hourly pay, and hours worked
Input #1, nom, wage, hrs
picPay.Print nom; hrs * wage Input #1, nom, wage,
hrs picPay.Print nom; hrs * wage
Close #1
End Sub