Apple IIe - Page 75

Applesoft BASIC Programming 75
ON, GOSUB Statement
The ON, GOSUB statement is very similar in nature to the ON,
GOTO statement. The fqllowing statement is an example of an
ON, GOSUB statemen1)
100 ON X GOSUB 1000, 2000, 3000
If the value of Xis 1, the subroutine at line 1000 is executed. If Xis
2, the subroutine at line 2000 is executed. If Xis 3, the subroutine
at line 3000 is executed. If X evaluates to 0 or to a number greater
than
3, the statement immediately following the ON, GOSUB
statement
will be executed.
If ON, GOSUB causes a branch to a subroutine, program control
will revert to the line immediately following the ON, GOSUB
statement,
once the subroutine has been executed.
Applesoft BASIC Functions
Functions are used in Applesoft BASIC to perform predefined
calculations or operations on their arguments. All functions use
the following format.
function (argument)
function is the keyword for the function. argument is a variable,
constant,
or expression which is to be stored in the operation
defined by the function.
The following statement is an example of the use of the SQR
function.
100 A= SQR(49)
In this example, A
would evaluate at 7. SQR is the keyword which
describes the square root function. The square root of 49 is, of
course, equal to 7.
Functions can be used with arithmetic, relational, and Boolean
expressions,
as shown in the following statement.