11.5.2.1 use the technical terms associated with arrays including upper and lower bounds 
11.5.2.3 write program code using 1D and 2D arrays 

Two dimentional arrays (Matrix)

A two-dimensional array (2D array) is an array where each element is represented by a one-dimensional array.

Each element of a two-dimensional array has two indices: row number (i) and column number (j).

Programmers usually indicate the line number of the variable i , the number of the column of the variable j.

You can get the value of an element by two indexes. For example,

arr[2][3]

A two-dimentional arra is used to create a table of data in rows and columns with the same data type.

Create 2D Array

We can create the two-dimensional array shown above:

$grid= array(
    array("", "", "", "A", ""),
    array("", "", "", "", " C "),
    array("", "", "", "", ""),
    array("", "", "B", "", ""),
    array("", "", "", "", "") );

An array $grid we can visually represent in a table:

$grid[0][3] = 'A'
$grid[3][2] = 'B'
$grid[1][4] = 'C'

2D iteration

Nested loops are used to iterate over all elements of a two-dimensional array.

FOR i = 0 to N

      FOR j = 0 to N 
            ...
     endFOR
endFOR
Examples:

Questions:

Exercises:

Tasks: