# 9.5. Code Practice with 2D Arrays¶

Replace the “ADD CODE HERE” below with the code to declare and create a 3 by 3 two-dimensional int array named `table`. The finished code will print the values 0 to 8.

Declaring and creating a 3 by 3 two-dimensional int array only takes one line. To declare the array specify the type of values in the array followed by `[][]` to indicate a 2D array and then provide a name for the array. To create the array add an `= new`, followed by the same type as before and `[num rows][num cols]`.

Replace the “ADD CODE HERE” below with the code to declare and initialize a two-dimensional String array called `students` with the names “Brice, Marvin, Anna” in the first row and “Kamal, Maria, Elissa” in the second. The finished code will print all the names in the array starting with all in the first row followed by all in the second row.

Print the values 47, 51, and 20 by accessing them in the the given two-dimensional array.

Print the values 8, 3, 87, and 34 by accessing them from the given two-dimensional array.

Print the number of rows in the given two-dimensional array, or the length of the outer array. Then print the number of columns, or the length of each inner array.

Ex. The array { {“hello”,”there”,”world”},{“how”,”are”,”you”} } should print:

Rows: 2

Columns: 3

Loop through the given two-dimensional array, printing out the values in the first row followed by those in the second row and so on.

Declare and create a two-dimensional array of strings named `colors`. Put the colors (“red”, “yellow”, “blue”) in the first row, and the colors (“orange”, “green”, “purple”) in the second row. Then print every value in the array.

Replace the “ADD CODE HERE” below with the code to count and print the number of 7’s that are in the 2d array. It should print 2.

Replace the “ADD CODE HERE” below with the code to print out the sum of the numbers in the second row of the “table” array. It should print 18.

Replace the “ADD CODE HERE” below with the code to find the sum of the values on the diagonal from [0][0] to [num rows - 1][num rows - 1] Print the sum. It should print 5.

Replace the “ADD CODE HERE” below with the code to declare and create a two-dimensional array of integers `numbers` with the numbers (1,2,3) in the first row, and the numbers (4,5,6) in the second row. Then loop through the two-dimensional array, printing out the values in the first row followed by those in the second row.

Replace the “ADD CODE HERE” below with the code to declare and create a two-dimensional array of integers `numbers` with the numbers (1,2,3) in the first row, the numbers (4,5,6) in the second row, and the numbers (7,8,9) in the third row. Then loop through the two-dimensional array, printing out the values in the first row followed by those in the second row and so on.

Given the following array, replace the “ADD CODE HERE” below with the code to replace the word “purple” with “yellow”.

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