Printing a multi-dimensional array with additional rows and columns

Question

I have a multidimensional array that stores some data, and I want to print it in a matrix form (so far no prolem), thing is I want to add a few columns and rows to make it readable. Something like this:

(the "inside square" is my actual 2d array)

My question is, what is the best way to do this?

My current code looks like this:

void printBoard(char board[N][N]) {
    for (int i = N-1; i >= 0; i--) {
        printf("%d %c ", i, BAR);
        for (int j = 0; j < N; j++) {
            printf("%c ", board[i][j]);
        }
        printf("\n");
    }
    for (int l = 0; l < 2; l++) {
        for(int k = -4; k < N; k++) {
            if(k < 0) {
                printf("%c", SPACE);
            }
            else {
               if(l == 0) {
                    printf("%c ", EMDASH);
                }
                else {
                    printf("%d ", k);
                }
            }
        }
            printf("\n");
    }
}

It works fine but feels rather messy. Also, if I change the size of my array to be more than 10 rows/columns, the numbers don't fit right. Is there a way to format this properly without changing the original array (the one I'm passing into the function)?

Thanks!

But then it doesn't work with double-digit numbers, it doesn't look like a straight table... — Anna
– Anna, Commented Dec 23, 2015 at 14:51

wdtj · Accepted Answer · 2015-12-23 18:08:06Z

2

You can control the width of the labels (number on right side and bottom) of the graph by specifying a width specifier on the printf format strings. That way, all the labels come out the same size. You can also specify a string like "--------------" (make it long enough to print your longest bar) and just print out the number limited by a width specifier.

Example:

printf("%*s ", length, "----------------------------------------");

edited Dec 23, 2015 at 18:08

answered Dec 23, 2015 at 14:55

wdtj

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5 Comments

ryyker Over a year ago

format string needs to include %s to accommodate 3rd argument in example.

wdtj Over a year ago

Aaah, quite so. Should have tested if first.

ryyker Over a year ago

Almost: for the arguments to be printed, an int and a string literal, the format specifier needs to contain both the d and s specifiers. Something like: "%d %s" will work. Or with padding modifiers: "%7d %s".

wdtj Over a year ago

Actually, the * modifier chews up length and the s format uses the string "-----"

ryyker Over a year ago

I just verified your printf() statement on my compiler. I really did not think it would work. But you are correct, it does. Thanks. I learned something. +1 for sticking with it.

ryyker · Accepted Answer · 2015-12-23 17:10:52Z

Use format specifiers and escape sequences to place text where you need it to appear. For example this code: (from a tutorial on printf and formatting)

#include<stdio.h>

main()
{
    int a,b;
    float c,d;

    a = 15;
    b = a / 2;
    printf("%d\n",b);
    printf("%3d\n",b);
    printf("%03d\n",b);

    c = 15.3;
    d = c / 3;
    printf("%3.2f\n",d);
}

Produces this output:

Of particular interest to you, as you are using integers, note the modifiers that can be used with the "%d" specifier below in the Format specifiers section:

Escape sequences:

\n (newline)
\t (tab)
\v (vertical tab)
\f (new page)
\b (backspace)
\r (carriage return)
\n (newline)

Example Format specifiers:

%d (print as a decimal integer)
%6d (print as a decimal integer with a width of at least 6 wide)    
%06d (same as previous, but buffered with zeros) (added)
%f (print as a floating point)
%4f (print as a floating point with a width of at least 4 wide)
%.4f (print as a floating point with a precision of four characters after the decimal point)
%3.2f (print as a floating point at least 3 wide and a precision of 2)

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