GWBASIC User's Manual

GW-BASIC User's Guide
Chapter 6
Constants, Variables, Expressions and Operators
After you have learned the fundamentals of programming in GW-BASIC, you will find that you
will want to write more complex programs. The information in this chapter will help you learn
more about the use of constants, variables, expressions, and operators in GW-BASIC, and how
they can be used to develop more sophisticated programs.
6.1 Constants
Constants are static values the GW-BASIC Interpreter uses during execution of your program.
There are two types of constants: string and numeric.
A string constant is a sequence of 0 to 255 alphanumeric characters enclosed in double quotation
marks. The following are sample string constants:
HELLO
$25,000.00
Number of Employees
Numeric constants can be positive or negative. When entering a numeric constant in GW-BASIC,
you should not type the commas. For instance, if the number 10,000 were to be entered as a
constant, it would be typed as 10000. There are five types of numeric constants: integer, fixedpoint,
floating-point, hexadecimal, and octal.
Constant Description
Integer Whole numbers between -32768 and +32767. They do not contain
decimal points.
Fixed-Point Positive or negative real numbers that contain decimal points.
Floating-Point Constants Positive or negative numbers represented in exponential form
(similar to scientific notation). A floating-point constant consists of
an optionally-signed integer or fixed-point number (the mantissa),
followed by the letter E and an optionally-signed integer (the
exponent). The allowable range for floating-point constants is
3.0×10 -39 to 1.7×10 38. For example:
235.988E-7=.0000235988
2359E6=2359000000
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