CODEWITHSUNDEEP
listrebolred-lang
rnso
rnso

Reputation: 24565

Creating a series of numbers in Red language

I have a few simple questions, hence I am putting them together:

  1. What is the best way to create a series of numbers. Following works but is there a simpler method like 1:10 available in some languages?

    myseries: []

    repeat i 10 [append myseries i]

    print myseries

(1a. Why is above code not making usual code block on this page?)

  1. Similarly, what is the best way to create a series of 10 elements, all initialized to 0 or ""? Do I have to use there also repeat i 10 or loop 10 and serially append an initially blank series?

  2. Also, should I specify the number of elements as in following code while creating the series initially? What is the disadvantage of not doing this?

    myseries: make block! 10

Thanks for your help.

Upvotes: 1

Views: 256

Answers (2)

draegtun
draegtun

Reputation: 22570

1) My preference would be to go with COLLECT here:

myseries: collect [repeat i 10 [keep i]]

2) See ARRAY function:

>> array/initial 10 0
== [0 0 0 0 0 0 0 0 0 0]

You can also pass it a anonymous function:

>> i: 0 array/initial 10 does [i: i + 1]
== [1 2 3 4 5 6 7 8 9 10]

3) Generally it is good practise to use myseries: make block! 10 (or just 0 if size of block is unknown) to avoid unnecessary gotchas! See To copy or not to copy, that is the question & Is REBOL a Pure Functional Language?

Upvotes: 6

sqlab
sqlab

Reputation: 6436

1) I do not know about a better way at this time, although on https://gitter.im/red/... there are discussions about a range data type or for implementations

a) It makes a block. You see that with probe myseries. What do you expect?

2) >> append/dup [] 0 10 == [0 0 0 0 0 0 0 0 0 0]

3) If you do not initialize/reserve the needed memory, Red has to make a guess how much memory is needed. This can be more than needed or less. If less then Red has to allocate another chunk of memory. This can happen a few times if you need more memory. Maybe it has to move around memory blocks too if it wants continuous memory, but I do not know about the strategy used.

Upvotes: 1

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