Propeller Manual

Table Of Contents

LOOKUP, LOOKUPZ – Spin Language Reference

Page 138 · Propeller Manual v1.1

LOOKUP, LOOKUPZ

Command: Get value from an indexed position within a list.

((PUB ┆ PRI))

LOOKUP ( Index : ExpressionList )

((PUB ┆ PRI))

LOOKUPZ ( Index : ExpressionList )

Returns: Value at the one-based Index position (LOOKUP) or zero-based Index position

(

LOOKUPZ) of ExpressionList, or 0 if out-of-range.

•

Index is an expression indicating the position of the desired value in ExpressionList.

For

LOOKUP, Index is one-based (1..N). For LOOKUPZ, Index is zero-based (0..N-1).

•

ExpressionList is a comma-separated list of expressions. Quoted strings of characters

are also allowed; they are treated as a comma-separated list of characters.

Explanation

LOOKUP and LOOKUPZ are commands that retrieve entries from a list of values. LOOKUP returns

the value from ExpressionList that is located in the one-based position (1..N) given by Index.

LOOKUPZ is just like LOOKUP except it uses a zero-based Index (0..N-1). For both commands, if

Index is out of range then 0 is returned.

Using LOOKUP or LOOKUPZ

LOOKUP and LOOKUPZ are useful for mapping a contiguous set of numbers (1, 2, 3, etc. –or– 0,

1, 2, etc.) to a set of non-contiguous numbers (45, -103, 18, etc.) where no algebraic

expression can be found to do so concisely. The following example assumes

Print is a

method created elsewhere.

PUB ShowList | Index, Temp

repeat Index from 1 to 7

Temp := lookup(Index: 25, 300, 2_510, 163, 17, 8_000, 3)

Print(Temp)

This example looks up all the values in LOOKUP’s ExpressionList and displays them. The

REPEAT loop counts with Index from 1 to 7. Each iteration of the loop, T LOOKUP uses Index to