This is a question I almost always get when giving the C/SIDE Introduction and/or C/SIDE Solution Development trainings so why not make a little blog item about it?

This is the syntax of the OPEN function for a dialog:

Dialog.OPEN(String [, Variable1], ...)

• This string contains the text you want the system to display in the window.
• Use a back slash (\) to start a new line.
• Use pound signs (#) to insert variable values into the string, place the pound signs where you want the system to substitute the variable value.
• If you use @ characters instead of #, the string can be used as an indicator. In this case, use @ characters only for the string, and let the variable be an integer.
• The limits of the indicator are 0 and 9999 - meaning that the integer you use for updating the indicator should have a value within this range.

Example in a Codeunit:

Declare 2 variables:

Then write this code:

Now run the Codeunit, result:

To summarize: