Lua Check for Value Against Array Elements

Question

Trying to teach myself Lua; I've gone through similar questions about this, and I still can't understand how to do this. The main thing that is confusing me is tables vs arrays. For the below code I'm just wanting check a given value against values I've populated into an array. However, something is going wrong. Thank for your time.

valueToCheckFor = 35    

sampleArray = {}
for i=30, 49, 1  do
  sampleArray[i] = i + 1
  print(i)
end    

for k = 0, #sampleArray, 1 do
    if valueToCheckFor == k then
        print(valueToCheckFor .. " is in the array.")
    else
        print(valueToCheckFor .. " is not in the array.")
    end
end

possible duplicate of Search for an item in a Lua list

hjpotter92
– hjpotter92

2014-04-08 20:18:22 +00:00
Commented Apr 8, 2014 at 20:18 — hjpotter92
– hjpotter92, Commented Apr 8, 2014 at 20:18

gwell · Accepted Answer · 2014-04-08 20:23:44Z

1

Here is your code written to be Lua array friendly:

valueToCheckFor = 35

sampleArray = {}
for i=30, 49  do
    -- add to end of array
    sampleArray[#sampleArray+1] = i + 1
    print(i+1)
end

-- check each value in array
for k = 1, #sampleArray do
    if valueToCheckFor == sampleArray[k] then
        print(valueToCheckFor .. " is in the array.")
    else
        print(valueToCheckFor .. " is not in the array.")
    end
end

answered Apr 8, 2014 at 20:23

gwell

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1 Comment

Oliver Over a year ago

@babyy on SO people aim to always backup their statements, that's how we all learn from each other. Truth is I don't see anything wrong with the stated soln, except that author should have explained what was wrong (which other answers have done, but they didn't provide fix).

lhf · Accepted Answer · 2014-04-08 20:14:00Z

1

You sampleArray is not a sequence because does not begin at 1 and so # cannot be used on it. See http://www.lua.org/manual/5.2/manual.html#3.4.6.

answered Apr 8, 2014 at 20:14

lhf

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Comments

Community · Accepted Answer · 2017-05-23 11:57:07Z

0

#sampleArray return 0 because your array is not started by 1

The array part is every key that starts with the number 1 and increases up until the first value that is nil

https://stackoverflow.com/a/9613573/1198482

edited May 23, 2017 at 11:57

CommunityBot

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answered Apr 8, 2014 at 20:21

Baba

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