4.20. Lua array

An array is a collection of elements of the same data type arranged in a certain order, which can be an one-dimensional array and a multi-dimensional array.

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

4.20.1. One-dimensional array #

One-dimensional array is the simplest array, and its logical structure is linear table. An one-dimensional array can be used for loop out the elements in the array, as an example:

Example #

array = {"Lua", "Tutorial"} for i= 0, 2 do print(array[i]) end 

The output of the above code execution is as follows:

nil Lua Tutorial 

As you can see, we can use an integer index to access the array elements andreturn if the known index has no value nil .

In Lua index value starts with 1, but you can also specify 0 to start.

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

Example #

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

The output of the above code execution is as follows:

-4 -2 0 2 4 

4.20.2. Multidimensional array #

A multi-dimensional array is an array corresponding to the index key of an array that contains an array or an one-dimensional array.

The following is an array multidimensional array of three rows and three columns:

Example #

-- Initialize array array = {} for i=1,3 do array[i] = {} for j=1,3 do array[i][j] = i*j end end -- Accessing Arrays for i=1,3 do for j=1,3 do print(array[i][j]) end end 

The output of the above code execution is as follows:

1 2 3 2 4 6 3 6 9 

Three-row, three-column array multidimensional array of different index keys:

Example #

-- Initialize array array = {} maxRows = 3 maxColumns = 3 for row=1,maxRows do for col=1,maxColumns do array[row*maxColumns +col] = row*col end end -- Initialize array for row=1,maxRows do for col=1,maxColumns do print(array[row*maxColumns +col]) end end 

The output of the above code execution is as follows:

1 2 3 2 4 6 3 6 9 

As you can see, in the above example, the array sets the specified index value to avoid the occurrence of nil value, which helps to save memory space.