I want to implement "Siamese method" generate a magic square which sum of every row, every coloum and two main diagonals sum to the sane number. ( "Siamese method" : https://en.wikipedia.org/wiki/Siamese_method) It should take user input for the square size.

I'm using C for implementation, but my algorithm run "segmentation fault" each time.

#include

#include

// Structure representing Square

// size: dimension(number of rows/columns) of the square

// array: 2D array of integers

typedef struct _Square {

int size;

int **array;

} Square;

int get_square_size();

Square * generate_magic(int size);

void write_to_file(char *filename, Square * square);

int main(int argc, char *argv[])

{

char buf[100];

int size;

Square* newsquare = generate_magic(get_square_size());

return 0;

}

/* get_square_size prompts the user for the magic square size

* checks if it is an odd number >= 3 and returns the number

*/

int get_square_size()

{

char buf[50];

int size;

printf("Enter size of magic square, must be odd. ");

fgets(buf,sizeof(buf),stdin);

sscanf(buf,"%d", &size);

printf("%d ", size);

return 0;

}

/* generate_magic constructs a magic square of size n

* using the Siamese algorithm and returns the Square struct

*/

Square * generate_magic(int n)

{

Square* ptr = (Square*)malloc(sizeof(Square));

ptr->size = n;

int num = n*n;

int *arr[n];

for(int i = 0; i < n; i++){

arr[i] = (int*)malloc(n*sizeof(int));

}

int mid = n/2 + 1;

arr[0][mid-1] = 1;

int row = 0;

int col = mid;

for(int i = 1; i<= num; i++){

if(row == 0)

row = n-1;

if( (col+1) % n == 0)

col = 0;

if(arr[row][col] != 0)

row = row + n;

if(row > n-1)

row = 0;

arr[row][col] = i;

}

for(int j = 0; j< num; j++){

for (int k = 0; k < num; k++){

printf("%d, ", arr[j][k]);

}

printf(" ");

}

ptr->array = arr;

return ptr;

}