Parallax BASIC Stamp 1, Programming Manual

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5: BASIC Stamp Command Reference – IF…THEN
BASIC Stamp Programming Manual 2.0c
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IF…THEN
BS1 BS2 BS2e BS2sx BS2p
IF Condition THEN Address
Function
Evaluate Condition and, if it is true, go to the point in the program marked
by Address.
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Condition
is a statement, such as “x = 7” that can be evaluated as
true or false. The Condition can be a very simple or very complex
relationship, as described below.
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Address
is a label that specifies where to go in the event that
Condition is true.
Quick Facts
BS1 BS2, BS2e, BS2sx and BS2p
Comparison
operators
=, <>, >, <, >=, <= =, <>, >, <, >=, <=
Conditional
logic operators
AND, OR NOT, AND, OR, XOR
Format of
condition
Variable Comparison Value
;where Value is a variable
or constant
Value1 Comparison Value2
;where Value1 and Value2 can by
any of variable, constant or
expression
Parentheses Not Allowed Allowed
Explanation
IF...THEN is PBASIC’s decision maker. It tests a condition and, if that
condition is true, goes to a point in the program specified by an address
label. The condition that IF...THEN tests is written as a mixture of
comparison and logic operators. The available comparison operators are:
Comparison Operator
Symbol
Definition
= Equal
<> Not Equal
> Greater Than
< Less Than
>= Greater Than or Equal To
<= Less Than or Equal To
Comparisons are always written in the form: Value1 Comparison Value2.
The values to be compared can be any combination of variables (any size),
1 2
e
2
sx
2
p
2
Table 5.23: IF…THEN Comparison
Operators.
NOTE: On the BS1, expressions
are not allowed as arguments.
Also, the Value1 (to the left of
comparison) must be a variable.
NOTE: Expressions are not allowed
as arguments on the BS1. The
range of the Pin argument on the
Table 5.22: IF…THEN Quick Facts.