Magic Square Code Help, want to know where it moves the number down Programming in C

Question

# include <stdio.h>
# include <stdlib.h>
int main(void)
{  
int s;
int row;
int column;
int k;
int array[99][99] ;

printf("Enter the dimension of the square : ") ;
scanf("%d", &s) ;

if (s % 2 == 0)
{
printf("Please enter an even number") ;
goto last;
}


column = (s + 1) / 2 ;
row = 1 ;

int sqr1 = s*s;

for(k = 1 ; k <= sqr1 ; k++)
{
array[row][column] = k ;
if(k % s == 0)
{
    row = (row + 1);
    goto loop ;
}
if(row == 1)
    row = s ;
else
         row = row - 1 ;
if(column == s)
    column = 1;
else
    column = column + 1 ;
    loop : ;
}
for (row = 1 ; row <= s ; row++)
{
for (column = 1 ; column <= s ; column++)
    {
    printf("%d\t", array[row][column]) ;
}
printf("\n\n") ;
}
last : ;
return 0;
}

I was wondering if anyone could tell me where the code puts the number down. Say I wanted a 3x3 magic square. The output would be:

https://i.stack.imgur.com/BYTSn.png

I was wondering where in the code it would move the 4 down because the 1 is already there. Same thing with the 7 moving down. The principle is you go 1 up and 1 to the right everytime and if there is something there you move down and keep going.

Aside: `"Please enter an even number"` --> `"Please enter an odd number"` — Weather Vane, Jun 21 '17 at 17:43
Did you read the Wikipedia page [Method for constructing a magic square of odd order](https://en.wikipedia.org/wiki/Magic_square#Method_for_constructing_a_magic_square_of_odd_order)? Or the [Siamese method](https://en.wikipedia.org/wiki/Siamese_method)? — Weather Vane, Jun 21 '17 at 17:55
Yes, I understand how it works, I was just wondering in the code where it shifts the number down instead of replacing the number already there in the array. In the case of the 3x3, the 4 shifts down instead of taking the spot of the 1 — rprog, Jun 21 '17 at 17:59
I would find it more interesting to write my own solution . . . — Weather Vane, Jun 21 '17 at 18:18
Well for a 3x3 square, you can work through the 9 positions by hand, with pencil and paper, to work out what is going on. — Weather Vane, Jun 21 '17 at 18:26
I know how the formula works, what I want to know is how they move down numbers in the program. — rprog, Jun 21 '17 at 18:28
...by working through the code line by line, is what I mean. If you are interested in how it works - work through it! — Weather Vane, Jun 21 '17 at 18:31

score 0 · Answer 1 · answered Jun 21 '17 at 18:28

What About:

#include <stdio.h>
#include <string.h>

#define  N  (3)

int main( int argc, char * argv[] )
{
    int square[ N ][ N ];

    int i = N / 2;
    int j = N - 1;
    int num = 1;

    memset( square, 0, sizeof(square) );

    while( num <= N * N )
    {
        if( (i == -1) && (j == N) )
        {
            i = 0;
            j = N - 2;
        }
        else
        {
            if( i < 0 )
                i = N - 1;

            if( j == N )
                j = 0;
        }

        if( square[i][j] )
        {
            i++;
            j = j - 2;

            continue;
        }
        else
        {
            square[i][j] = num;
            num++;
        }

        j++;
        i--;
    }

    printf("N   = %d\n", N );
    printf("Sum = %d\n\n", N * (N * N + 1) / 2 );

    for( i = 0; i < N; i++ )
    {
        for( j = 0; j < N; j++ )
            printf("%3d ", square[i][j]);

        printf("\n");
    }

    return 0;
}

Outputs:

N   = 3
Sum = 15

  2   7   6 
  9   5   1 
  4   3   8 

N   = 5
Sum = 65

  9   3  22  16  15 
  2  21  20  14   8 
 25  19  13   7   1 
 18  12   6   5  24 
 11  10   4  23  17

N   = 7
Sum = 175

 20  12   4  45  37  29  28 
 11   3  44  36  35  27  19 
  2  43  42  34  26  18  10 
 49  41  33  25  17   9   1 
 40  32  24  16   8   7  48 
 31  23  15  14   6  47  39 
 22  21  13   5  46  38  30 

N   = 9
Sum = 369

 35  25  15   5  76  66  56  46  45 
 24  14   4  75  65  55  54  44  34 
 13   3  74  64  63  53  43  33  23 
  2  73  72  62  52  42  32  22  12 
 81  71  61  51  41  31  21  11   1 
 70  60  50  40  30  20  10   9  80 
 59  49  39  29  19  18   8  79  69 
 48  38  28  27  17   7  78  68  58 
 37  36  26  16   6  77  67  57  47

References:

Magic Square Code Help, want to know where it moves the number down Programming in C

1 Answers1