' Convert grams to kilograms
'
PRINT "Enter number of grams" 
INPUT GRAMS
PRINT "Number of kilograms:", GRAMS / 1000
END

Prompting the User

Say the above program were run and that the user entered 734 grams. The monitor would look like:

Enter number of grams
? 734
Number of kilograms:    0.734

The string "Enter number of grams" is called a prompt. A prompt is a short phrase which tells the user of a computer program what is expected. The program is said to prompt the user for input.

You should be careful that the prompt makes sense to the user of a program. The prompt is for the user; it doesn't "tell" the INPUT statement what to do. Here is a poorly written version of the "grams to kilograms" program:

' Convert grams to kilograms
PRINT "Enter number" 
INPUT GRAMS
PRINT "result:", GRAMS / 1000
END

When this program is run, and the user enters data as before, the user sees:

Enter number
? 734
result:    0.734

The answer is correct, and Mr. Spock might be happy with the program (since "logically" the two programs are the same). But the second version is not user-friendly and is prone to user error. Maybe the user though the program was converting ounces to pounds. Nothing on the monitor would correct this mistaken notion.