Character I/O:
Visual
Basic provides some excellent ways for input and output operations.
Input can be taken using TextBox, InputBox, and output can be shown with
the Print method, TextBox, Label, PictureBox and MsgBox.
Example:
In the above program, Input is taken using Text1 and output is shown in Text2, where output is the incremented value of the input.
Input and output using TextBox
The TextBox Control provides an efficient way for both input and operations. The following sample program shows it.
Example:
Private Sub Command1_Click()
Dim a As Integer
a = Val(Text1.Text)
a = a + 1
Text2.Text = a
End Sub
Dim a As Integer
a = Val(Text1.Text)
a = a + 1
Text2.Text = a
End Sub
In the above program, Input is taken using Text1 and output is shown in Text2, where output is the incremented value of the input.
- Download sample program: Sum Calculator
The Sum Calculator program is explained here: Some simple VB6 examples.
InputBox
InputBox is a function that prompts for user-input. InputBox shows a dialog box that inputs value from the user.Syntax:
a=InputBox( promt, [Title], [Default], [xpos], [ypos])
where 'a' is a variable to which the value will be assigned. The texts inside the InputBox are optional except the "prompt" text. "prompt" text is the prompt message. "title" is the title of the message box window. "Default" is the default value given by the programmer. 'xpos' and 'ypos' are the geometric positions with respect to x and y axis respectively.
Note: Parameters in brackets are always optional. Do not write the brackets in your program.
Example:
Private Sub cmdTakeInput_Click()
Dim n As Integer
n = InputBox("Enter the value of n : ")
Print n
End Sub
Dim n As Integer
n = InputBox("Enter the value of n : ")
Print n
End Sub
The above program prints the value of n taken from the InputBox function.
Example: InputBox with the title text and default value.
Private Sub cmdTakeInput_Click()
Dim n As Integer
n = InputBox("Enter the value of n : ", "Input", 5)
Print n
End Sub
Dim n As Integer
n = InputBox("Enter the value of n : ", "Input", 5)
Print n
End Sub
The InputBox dialog appears with the title "Input" and the highlighted default value in the provided text field is 5.
MsgBox
The MsgBox function shows a dialog box displaying the output value or a message.
Syntax:
MsgBox Prompt, [MsgBox style], [Title]
where Promt text is the prompt message, [MsgBox Style] is the msgbox style constants and [Title] is the text displayed in the title bar of the MsgBox dialog.
Example:
Example: MsgBox with the dialog type and title text.
The MsgBox dialog box appears with the 'vbInformation' dialog type and the title text is '"Result".
The list of dialog types is shown in the Quick Info text upon entering the Prompt text.
where Promt text is the prompt message, [MsgBox Style] is the msgbox style constants and [Title] is the text displayed in the title bar of the MsgBox dialog.
Example:
Private Sub cmdShowMessage_Click()
Dim n As Integer
n = 10
MsgBox "The value of n is " & n
End Sub
Dim n As Integer
n = 10
MsgBox "The value of n is " & n
End Sub
Example: MsgBox with the dialog type and title text.
Private Sub cmdShowMessage_Click()
Dim n As Integer
n = 10
MsgBox "The value of n is ", vbInformation, "Result" & n
End Sub
Dim n As Integer
n = 10
MsgBox "The value of n is ", vbInformation, "Result" & n
End Sub
The MsgBox dialog box appears with the 'vbInformation' dialog type and the title text is '"Result".
The list of dialog types is shown in the Quick Info text upon entering the Prompt text.
Download the following programs:
The above programs are explained here: VB6 source code for beginners.
Example: The following program shows how the MsgBox function returns value.
Private Sub Command1_Click()
n = MsgBox("hello", vbOKCancel)
If n = 1 Then
Print "You have pressed ok"
ElseIf n = 2 Then
Print "You have pressed cancel"
End If
End Sub
n = MsgBox("hello", vbOKCancel)
If n = 1 Then
Print "You have pressed ok"
ElseIf n = 2 Then
Print "You have pressed cancel"
End If
End Sub
When you click the
button, the MsgBox dialog appears. Then the user either presses Ok or
Cancel in this case. The MsgBox function returns 1 if you press Ok, it
returns 2 if you press Cancel.
Example:
Line continuation character( _)
In your vb program you can type maximum of 1023 characters in a line. And sometimes, it doesn't fit in the window when we write so many characters in a line. So Line Continuation Character (underscore preceded by a space) is used to continue the same statement in the next line.Example:
Private Sub cmdShow_Click()
MsgBox "Hello, welcome to www.vbtutes.com", _
vbInformation, "Welcome"
End Sub
MsgBox "Hello, welcome to www.vbtutes.com", _
vbInformation, "Welcome"
End Sub
Output using PictureBox
PictureBox is also used for the output operation. The output is displayed using the Print method.Example:
Private Sub cmdDisplay_Click()
Dim n As Integer
n = 40
picResult.Print n + 5
End Sub
Dim n As Integer
n = 40
picResult.Print n + 5
End Sub
The program prints 45 in the PictureBox.
- Download sample program: Output with PictureBox
Input-output with File
Input-output operations
are also possible using File in Visual Basic discussed in the
appropriate lessons. In this case, the input is taken from the data
saved in Windows Notepad , in .txt extension and output can be displayed
in the same file.
Output to the printer
The output can be
displayed using printer . Visual Basic easily lets you display the
output value or the output message using printer. Visual Basic treats
the printer as an object named Printer. This topic is discussed in the
appropriate lesson.
