# Help with writing a program that creates an odd n*n magic square where n is...

• 11-20-2012
blisman20
Help with writing a program that creates an odd n*n magic square where n is...
I am in a beginning C programming class and I have this assignment: Write a program that creates an N*N magic square, i.e., a square arrangement of the numbers 1,2,…,N^2 in which the sum of rows, columns, and diagonals are the same. The user will specify the size of the square matrix: N. The value N must be an odd number between 1 and 15.

I am using visual studio 2010. Also I am only allowed to use C89. My program will not compile and I have been trying to fix my problems, but I still have a few left that I cannot figure out. I understand that my main problem is visual studio doesn't support variable array size so I tried to compensate for this, but clearly I failed. I would really appreciate any help because this program is really frustrating me!

Thank you!

PHP Code:

```  error C2057: expected constant expression1 error C2466: cannot allocate an array of constant size 0error C2057: expected constant expression error C2466: cannot allocate an array of constant size 0 error C2087: 'magic_square' : missing subscripterror C2133: 'magic_square' : unknown sizeerror C2143: syntax error : missing ';' before ')'error C2143: syntax error : missing ';' before ')'  ```

Code:

```#include <stdio.h>#define array_size 15 int main (void) {         int row, column, row1, column1, size, n = 2, magic_square [array_size][array_size];                 for ( ; ; ) {         printf ("Enter size of magic square: ");         scanf ("%d", &size);         if (size % 2 == 0)                 printf ("Enter an odd number!\n");         else if (size <= 0 || size > 15)                 printf ("Enter a number between 1 and 15!\n");         else {                 int magic_square [size][size];                 for (row = 0; row < size; row++)                         for (column = 0; column < size; column++)                                 magic_square [row][column] = 0;                 row = 0;                 column = (size/2);                 magic_square [row][column] = 1;                 for (n, n<= size*size, n++) {                         if (--row < 0)                                 row = (size -1);                         if (++column > size -1)                                 col = 0;                         if (magic_square [row][column] != 0) {                                 if (++row > (size -1))                                         row = 0;                                 if (--column < 0)                                         col = size - 1;                                 while (magic_square [row][column] != 0)                                         if (++row > (size -1))                                                 row = 0;                         }                         magic_square [row][column] = n;                 }                                 for (row = 0; row < size; row++)                                 for (column = 0; column < size; column++)                                 printf ("%4d\n", magic_square [row][column]);         }         }         return 0; }```
• 11-20-2012
qny
Easy solution: just define the array with a big enough size (15x15) and ignore the unused elements if the user asks for a smaller one.
• 11-20-2012
kcpilot
for (n, n<= size*size, n++) You sure you want to do this? Just a suggestion, but start with a 3X3 array to see if you have the code working properly
• 11-20-2012
blisman20
I thought I did define the array with my header: #define array_size 15
• 11-20-2012
blisman20
Okay actually I think I understsand what you're saying. I changed my magic_square [size][size] to magic_square [array_size][array_size], but I still have this error twice: error C2143: syntax error : missing ';' before ')'
• 11-20-2012
Matticus
Hint: Refer to post #3 above.