how to count number of sub array in lua string

Question

how to count number of sub array in lua string.

I have a lua string in following format,

{{"engName1":"Test1","validDurPeriod":0,"appStatus":2,"engName3":"", "ExtraInfo":{"returnPeriod":7,"stayType":50,"fingerprintInd":49,"stayPeriod":6,"medicalInd":49},} {"engName1":"Test2","validDurPeriod":3,"appStatus":2,"engName3":"", }, {"engName1":"Test3","validDurPeriod":2,"appStatus":2,"engName3":"","ExtraInfo":{"returnPeriod":7,"stayType":50,"fingerprintInd":49,"stayPeriod":6,"medicalInd":49} }, {"engName1":"Test4","validDurPeriod":3,"appStatus":2,"engName3":"", },}

I want to count number of sub arrays in lua string , something like {{},{},{},{}} as here count is 4

I tried something below code to check its contains array but not able to get the exact count. below code is working for single array but not working for multiple array

function checkType(sample)

if string.startswith(sample, "{{", true) or string.startswith(sample, "{ {", true)  or string.startswith(sample, "{  {", true) then
 return true;
else
return false;
end
end

Why do you need to count these? What are you trying to achieve? — lhf
– lhf, Commented Jun 14, 2014 at 13:44

lhf · Accepted Answer · 2014-06-14 13:44:23Z

1

If s contains your string, then n below contains the count:

local _,n=s:gsub("[^{}]",""):gsub("{}","")

answered Jun 14, 2014 at 13:44

lhf

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1 Comment

pravin chavan Over a year ago

Why do you need to count these? Depending on number of elements found in string I need to run a for loop and display these values.

semkeijsper · Accepted Answer · 2014-06-15 16:43:33Z

0

If your table works correctly, you should be able to use the function table.getn(table).

Examples:

print(table.getn{10,2,4})          --> 3
print(table.getn{10,2,nil})        --> 2
print(table.getn{n=1000})          --> 1000

a = {}
print(table.getn(a))               --> 0

I hope that does the trick ;)

Source: 19.1 - Array Size

answered Jun 15, 2014 at 16:43

semkeijsper

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1 Comment

nonchip Over a year ago

wouldn't just #a be better, also because of forward compatibility to 5.2?

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