Lua array

An array is a collection of elements of the same data type arranged in a certain order. It can be a one-dimensional array or a multi-dimensional array.

The index key value of Lua array can be represented by an integer, and the size of the array is not fixed.

---

One-dimensional array

One-dimensional array is the simplest array, and its logical structure is a linear table. One-dimensional arrays can use for to loop out the elements in the array, as shown in the following example:

array = {"Lua", "Tutorial"}

for i= 0, 2 do
   print(array[i])
end

The output result of the execution of the above code is:

nil
Lua
Tutorial

##As you can see Yes, we can access an array element using an integer index, returning nil if the known index has no value.

In Lua index values ​​start with 1, but you can also specify 0 to start.

In addition, we can also use negative numbers as array index values:

array = {}

for i= -2, 2 do
   array[i] = i *2
end

for i = -2,2 do
   print(array[i])
end

The above code execution output result is:

-4
-2
0
2
4

---

Multidimensional array

A multi-dimensional array means that the array contains an array or the index key of a one-dimensional array corresponds to an array.

The following is a three-row, three-column array multi-dimensional array:

-- 初始化数组
array = {}
for i=1,3 do
   array[i] = {}
      for j=1,3 do
         array[i][j] = i*j
      end
end

-- 访问数组
for i=1,3 do
   for j=1,3 do
      print(array[i][j])
   end
end

The above code execution output result is:

1
2
3
2
4
6
3
6
9

A three-row, three-column array multi-dimensional array with different index keys ：

-- 初始化数组
array = {}
maxRows = 3
maxColumns = 3
for row=1,maxRows do
   for col=1,maxColumns do
      array[row*maxColumns +col] = row*col
   end
end

-- 访问数组
for row=1,maxRows do
   for col=1,maxColumns do
      print(array[row*maxColumns +col])
   end
end

The output result of the execution of the above code is:

1
2
3
2
4
6
3
6
9

As you can see, in the above example, the array is set to the specified index value, which can avoid nil values. Helps save memory space.