MHB Create a multiplication table program

[carl123]

Create a program in C++ that makes a multiplication table. Ask the user how many numbers should be in the table.

Requirements
Store all of the data in a 2-dimensional vector of ints.
Allow the program to run repeatedly until the user is finished.
Do not allow inputs outside the range of 1-9

Sample Run
Enter the numbers for multiplication table (1-9): -1Enter the numbers for multiplication table (1-9): 10Enter the numbers for multiplication table (1-9): 4 | 1 2 3 4
- | - - - -
1 | 1 2 3 4
2 | 2 4 6 8
3 | 3 6 9 12
4 | 4 8 12 16

| 4 3 2 1
- | - - - -
4 | 16 12 8 4
3 | 12 9 6 3
2 | 8 6 4 2
1 | 4 3 2 1

Do you want to do another? (y/n) y

Enter the numbers for multiplication table (1-9): 3 | 1 2 3
- | - - -
1 | 1 2 3
2 | 2 4 6
3 | 3 6 9

| 3 2 1
- | - - -
3 | 9 6 3
2 | 6 4 2
1 | 3 2 1

Do you want to do another? (y/n) n

Things to Consider

You can use setw(n) before any number and it will add blank spaces to show the number in n columns. That is how to line up your columns.
Don't forget you have 0 based indexes and numbers that go from 1 to 9.

 

[Evgeny.Makarov]

Please read rule #11 (click on "Expand" button in the beginning of the page) and Mark's remark in https://driven2services.com/staging/mh/index.php?posts/75931/. To demonstrate your effort, you could describe what you know and don't know how to do in this problem.

 

[jza]

Create a program in C++ that makes a multiplication table. Ask the user how many numbers should be in the table.

This is a simple problem to test your understanding of 2D arrays.

You could approach it in the standard way, like this (porting the code from Python to C++ is left as an exercise to the reader ;) ):

def multi_table_(n):
    A = [[0 for i in xrange(0, n)] for j in xrange(0,n)]
    for i in xrange(0, n):
        for j in xrange(0, n):
            A[i][j] = (i + 1) * (j + 1);    print A

But you'd be wasting some computing power. You could recognise the symmetry in the matrix and approach it like this instead:

def multi_table(n):
    A = [[0 for i in xrange(0, n)] for j in xrange(0,n)]
    for i in xrange(0, n):
        for j in xrange(i, n):
            A[i][j] = (i + 1) * (j + 1);
            A[j][i] = A[i][j]    print A