PROGRAMMING TECHNIQUES

DATA CONVERSIONS

When necessary, the CBM BASIC Interpreter will convert a numeric data item from an integer to floating-point. or vice-versa, according to the following rules:

• All arithmetic and relational operations are performed in floating point format. Integers are converted to floating-point form for evaluation of the expression, and the result is converted back to integer. logical operations convert their operands to integers an return an integer result.
• If a numeric variable name of one type is set equal to a numeric data item of a different type, the number will be converted and stored as the data type declared in the variable name.
• When a floating-point value is converted to an integer, the fractional portion is truncated (eliminated) and the integer result is less than or equal to the floating-point value. If the result is outside the range of +32767 thru -32768, the BASIC error message ?ILLEGAL QUANTITY will occur.

USING THE INPUT STATEMENT

Now that you know what variables are, let's take that information an put it together with the INPUT statement for some practical programming applications.

In our first example, you can think of a variable as a "storage compartment" where the Commodore 64 stores the user's response to your prompt question. To write a program which asks the user to type in a name, you might assign the variable N$ to the name typed in. Now every time you PRINT N$ in your program, the Commodore 64 will automatically PRINT the name that the user typed in.

Type the word NEW on your Commodore 64. Hit the <RETURN> key and try this example:

   10 PRINT"YOUR NAME": INPUT N$
   20 PRINT"HELLO",N$