Lua Quick Start Guide

Sparse arrays

Arrays can be sparse, meaning an array can have a hole in it. Elements can be assigned to index 1 and 2 of an array, leaving 3 and 4 blank and then assigning elements 5 and 6. Any hole in the array will have a default value of nil, as the following code segment demonstrates:

arr = { }arr[1] = "x"arr[2] = "y"-- arr[3] is nil by default-- arr[4] is nil by defaultarr[5] = "z"arr[6] = "w"for i=1,6 do    print (tostring(arr[i]))end

This implies that setting the value of an existing index to nil will introduce a hole in the array. These holes can sometimes cause unexpected issues.