myArray = {first = "a", "b", second = "c"}
print(myArray[1], myArray[2], myArray.first, myArray.second, #myArray) -- b nil a c 1
myArray[6] = "d"
print(myArray[1], myArray[2], myArray[6], myArray.first, myArray.second,
#myArray) -- b nil d a c 1
myArray = {first = "a", "b", "b2", second = "c"}
print(myArray[1], myArray[2], myArray.first, myArray.second, #myArray) -- b nil a c 1
myArray[6] = "d"
print(myArray[1], myArray[2], myArray[6], myArray.first, myArray.second,
#myArray) -- b nil d a c 2
结论：
lua的table对象中index和key对象是互不影响的；
而且#table会在不连续定义index的时候断裂，直接取前面获取到的个数：第2个和第四个的#myArray输出可以看出，第一次定义了"b",index为1，后面加了键值对second之后即使赋值了myarray[6]，length还是1. 而第二次给myArray赋值定义了"b","b2"，是个连续的，所以length就为2.
原文：https://www.cnblogs.com/guaguadache/p/14836810.html