Unit6-04: 2D Arrays (Optional)

Learning Outcome

At the end of this lesson, you will be able to:

• understand and use a 2D arrays (or lists in Python) 

Review

• arrays and for..each loops

Here is the Problem:

• Create a program called “2D Arrays” that asks the user for the number of rows and columns and then creates a 2D array of that size.

• The program uses 2 loops (a loop inside a loop) to generate random numbers between 1 and 50 and display them to the user. It then places the numbers into the 2D array (a list in Python or an array in C++).

  • You will need the following constants in both Python and C++:

    • MIN_NUM = 1

    • MAX_NUM = 50

  • To declare an array in C++, use the following:

    • #include <array>

    • std::array<int, MAX_ARRAY_SIZE> arrayOfInt;

  • In C++, you cannot create the array dynamically like you can in Python. You will have to decide on the size of the array beforehand. Use:

    • const int NUM_ROWS = 5;

    • const int NUM_COLUMNS = 7;

  • We will use the following to generate a random number in C++:

    • #include <time.h>

    • srand(time(NULL));

    • randomNumber = (rand() % MAX_VALUE) + MIN_VALUE;

• The program has a function called “cal_average()” in Python and “calcAverage()” in C++.

  • It accepts a 2D array as a parameter.

  • The function MUST use a loop to calculate the sum. Then use the following formula to calculate the average:

    • average = sum / number_of numbers

    • Remember that average can be a decimal!

    • Do NOT use a  built-in function to calculate the average.

  • It returns a single variable - the min value in the array (or list).

• The average will then get displayed in main().

  • Do NOT use a hard-coded number (i.e. 10). Use the built-in length / size() functions.

    • In Python, use:

      • len(list_of_int) 

    • In C++, use:

      • #include <array>

      • arrayOfInt.size()

• Since your data is random, it is not possible to create test cases in advance. 

  • Instead, insert 3 test cases of your program output. Then visually check to make sure your output is correct.

Note: The top-down design should be for the entire program. There should be a flowchart for each function.

Activity

• in groups of 2, do the following on the board for today's daily assignment:

  • Top-Down Design

  • Flow Chart

  • Pseudocode

  • Test Cases

Daily Assignment

• complete the Daily Assignment section in Hãpara Workspace for this day

  • if Hãpara is not working, make a copy of this document

  • move it to your IMH-ICS folder for this course

Extra

• recreate the same program in C++