Thread: Help with multidimensional array

I'm trying to make a multiplication table using a multidimensional array and I keep having problems with the first row and 0's.

I need to print a table that looks like this

* 1 2 3
1 1 2 3
2 2 4 6
3 3 6 9

I tried using (row * column) but I can't figure out how to get rid of the 0's which are throwing everything off. If I start the loops at =1 it does something crazy and throws in random numbers. I also have NO idea how to get the * symbol in the beginning.

This is what I have right now any help would be greatly appreciated. I need to understand what I'm doing wrong not just given a correction to a part of the code. Thanks again in advance.

Code:

#include <stdio.h>

const int num_rows = 10;
const int num_columns = 10;

int main (void)
{
    int box[num_rows][num_columns];
    int row, column;

    for (row = 0; row < num_rows; row++)
        for (column = 0; column < num_columns; column++)
            box[row][column] = row * column;

    for (row = 0; row < num_rows; row++)
        {
            for(column = 0; column < num_columns; column++)
            {
                printf("%4d", box[row][column]);
            }
        printf("\n");
        }
    return 0;
}

First, * 1 2 3 ... are really numbers, you have to print this line as characters, OK? When you are printing out your rows, that first entry is not a number, but again, a character. Think of it as printing your results inside the fence line of

* 1 2 3 4 5 6 ...
1
2
3
4
5
.
.
.
That will probably help you continue to solve your problem. You're not really doing anything wrong, you just had the wrong idea how to print your results.

This gives the desired output format, but does not use a 2d array. I assume this is for an assignment and as per the homework policy on this board I removed the 2d array. But you can use this as a template to see how to output formatted tables.

Code:

#include <stdio.h>

const int num_rows = 10;
const int num_columns = 10;

int main (void)
{
    int row, column;

    // print column header
    printf("%-4c", '*');
    for (column = 1; column < num_columns; column++)
        printf("%-4d", column);
    putchar('\n');
    
    for (row = 1; row < num_rows; row++)
    {
        printf("%-4d", row);
        for(column = 1; column < num_columns; column++)
        {
            printf("%-4d", row * column);
        }
        printf("\n");
    }
    getchar();
    return 0;
}