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Visual Basic 6 Programming. Decide how many variables you need by looking at this form. There is one textbox for input and there are 3 labels for output, so you need 4 variables in all Textbox names should start with txt Labels names should start with lbl
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Visual Basic 6 Programming • Decide how many variables you need by looking at this form. There is one textbox for input and there are 3 labels for output, so you need 4 variables in all • Textbox names should start with txt • Labels names should start with lbl • Command button names should start with cmd
Visual Basic 6 Programming • Numeric variables should start with sgl (for single) • Text variables should start with str (for string) Variable & Object Naming Conventions TxtPrice will have a corresponding variable sglPrice LblGST will have a corresponding variable sglGST LblPST will have a corresponding variable sglPST LblTotal will have a corresponding variable sglTotal
Visual Basic 6 Programming Variables section Dim sglPrice as single 'this is to store the price Dim sglGST as single Dim sglPST as single Dim sglTotal as single • Use an apostrophe to make comments: 'This is a comment it will appear green • Variables are locations in the computer memory • Objects on the form (textboxes etc) are what the user interacts with.
Visual Basic 6 Programming INPUT section • This is where the input the user types into a textbox is passed onto the variable • In order to convert text from the textbox into a number, you use the val() function: SglPrice = val(txtPrice.text) strName = txtName.text strName = “Joe” ‘Notice the double quotes around Joe • DO NOT use val if you are assigning a value to a text variable (string variable)! • Notice the variable getting assigned a value is always on the left side of the = sign
Visual Basic 6 Programming Calculation section • should only use variables (just like in math!) • There are 3 calculations in this case sglGST = sglPrice * 0.05 sglPST = sglPrice * 0.05 sglTotal = sglPrice + sglGST + sglPST • Again, notice that the variable being assigned a value MUST be on the left side of the = sign. • DON’T use OBJECTS in this section (txt or lbl)
Visual Basic 6 Programming OUPUT Section • You will now have to output the 3 output variables to the 3 corresponding labels lblGST.caption = sglGST lblPST.caption = sglPST lblTotal.caption = sglTotal
This program responds to the change event. When the user types in something into the textbox, the program executes. TxtPrice LblGST LblTotal LblPST
Visual Basic 6 Programming Reminders • Textboxes have a text property • Labels, Command buttons, and Forms have a caption property