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Chapter

Basics

the

BASIC

Language

Since all the variables in the BASIC program are treated as global variables, passing

arguments to subroutines is meaningless and enclosing arguments in the brackets of the

subroutines will lead to a syntax error while compiling.

A subroutine in BASIC can be recursive, which means it can call itself or other subroutines

that in turn call the first subroutine. The following sample program contains a recursive

subroutine - Factorial, to calculate the value of n! ("n factorial").

PRINT "Please enter a number (1 - 13):"

INPUT N%

FactResult! = 1

Fact% = N%

GOSUB Factorial

PRINT N%, "! = ", FactResult

Loop:

GOTO Loop

Factorial:

IF Fact% < 1 THEN RETURN

FactResult! = FactResult! * Fact%

Fact% = Fact% -1

GOSUB Factorial

RETURN

4.7 Programming Style

The following are the guidelines used in writing programs in this manual, including the

sample program. These guidelines are recommended for program readability, but they are

not compulsory.

 Reserved words and symbolic constants appear in uppercase letters:

PRINT "Portable Terminal Demo Program"

BEEP(800,30,0,5,800,15,0,5,800,15)

 Variable names are in lowercase with an initial capital letter. If variable names are

combined with more than one part, other capital letters may be used to make it easier to

read:

ProcessFlag% = 0

Temp$ = GET_RECORD$(3,1)

 Line labels are used instead of line numbers:

ON READER(2) GOSUB GetSlotReader

1 2 ... 22 23 24 25 26 27 28 29 30 31 32 ... 197 198

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Metrologic IS1000 Series Guía de usuario Pagina 27