table.insert

From TableLibraryTutorial of lua-users.org. Insert a given value into a table. If a position is given insert the value before the element currently at that position: > t = { 1,3,"four" } > table.insert(t, 2, "two") -- insert "two" at position before element 2 > = table.concat(t, ", ") 1, two, 3, four If no position is specified we append the value to the end of the table: > table.insert(t, 5) -- no position given so append to end > = table.concat(t, ", ") 1, two, 3, four, 5 When a table has an element inserted both the size of the table and the element indices are updated: > t = { 1,"two",3 } -- create a table > = table.getn(t) -- find current size 3 > table.foreach(t, print) -- display the table contents 1 1 2 two 3 3 > table.insert(t, 1, "inserted") -- insert an element at the start > = table.concat(t, ", ") -- see what we have inserted, 1, two, 3 > = table.getn(t) -- find the size 4 > table.foreach(t, print) -- the indexes have been updated 1 inserted 2 1 3 two 4 3 When no position is specified the element is inserted at the end of the table according to the calculated size. The size of a table may be user specified and not reflect the number of elements, e.g., > t = { 1,"two",3; n=10 } -- create a table with user size > table.insert(t, "end") -- insert with no position inserts at "end" > table.foreach(t, print) -- display the table contents 1 1 2 two 3 3 11 end n 11