GNVQ
Intermediate IT Optional Unit5
Tutors Sue Cahill and Colin Duley
GNVQ IT Intermediate - Visual Basic Notes 4
Communicating with the user
MESSAGE BOXES
In the programs that you have written so far, you have used Text
and Label boxes when you wanted to give the user an instruction or information
(“Please enter your name”) or if you wanted the user to type in some data
(e.g. the speed of the rocket).
Input boxes and message boxes provide another way of doing this.
To use a message box to send a message to the user we use it as a
statement. It takes the general form: -
-
MsgBox message, typecode, title
where both the message and title are strings, (they can be straight
text in quote marks or string variables or functions or combinations of
these)
In the following example the title field is omitted
-
MsgBox "The answer was " & Ans, 48
The typecode is a number that is formed by adding together the codes
that control which buttons are to appear, which symbol is to be displayed
and which button is to be highlighted when the box opens.
| Button Codes |
|
|
Symbols |
|
| 0 |
OK |
|
0 |
None |
| 1 |
OK and Cancel |
|
16 |
|
| 2 |
Abort, Retry and Ignore |
|
32 |
|
| 3 |
Yes, No and Cancel |
|
48 |
|
| 4 |
Yes and No |
|
64 |
|
| 5 |
Retry and Cancel |
|
|
|
Default Button
-
0 First
-
256 Second
-
512 Third
Where MsgBox is only being used for output, the buttons are not necessary,
so the only valid typecodes are 0, 16, 32, 48, 64.
If you don’t want to display a symbol, then the typecode can be omitted
altogether
-
i.e. MsgBox message,, title
If you want to use a message box to collect a reply, then it must be
used as a function. It takes the general format
-
reply = MsgBox(prompt, typecode, title)
The value returned by the function will tell us which button was clicked.
| Value Button |
|
Value Button |
|
| 1 |
OK |
2 |
Cancel |
| 3 |
Abort |
4 |
Retry |
| 5 |
Ignore |
6 |
Yes |
| 7 |
No |
|
|
INPUT BOXES
An input box is always used as a function
-
e.g. result = InputBox(prompt,title,default_value)
There is no typecode, an input box will always display OK and Cancel
and does not hold symbols. The default value is a string that can
be displayed in the entry slot of the box and will be returned if the user
presses OK.
