Question

insert code in all TODO part, it's about pointer. atmel studio 7.0. this should be able to run without utilities.h

// includes
#include <asf.h>

// function prototypes
// these are necessary if you are going to call a function before it is declared
// without these, we would have to put all of our functions above main
static void configure_console(void);
void get_matrix(int *matrix);
int calc_det(int *matrix);
void get_matrix_global(void);

// declare global variables
int matrix_global[9];

int main (void)
{
   // configure system
   board_init();
   sysclk_init();
   configure_console();

   printf("\nStarting Determinant Calculator\r\n\n");

   // declare constants
   const int NUM_METHODS = 3;
  
   // declare button variables
   bool prev_button_state = BUTTON_0_INACTIVE;
   bool current_button_state = BUTTON_0_INACTIVE;
  
   // create a fixed-sized int array with 9 elements and initialize elements to 0
   // name = matrix_array
   /***TODO - 1 line***/
  
   // create an int pointer and point it to NULL
   // name = matrix_dynamic
   /***TODO - 1 line***/
  
   // create an int pointer and point it to NULL
   // name = matrix
   /***TODO - 1 line***/
  
   // create a variable to keep up with what method to run
   int method = 0;
  
   // create a variable for the determinant that you calculate
   int det = 0;
  
   while (1)
   {
       // typical edge detection for button
       current_button_state = ioport_get_pin_level(BUTTON_0_PIN);
       if ( (current_button_state == BUTTON_0_ACTIVE) && (prev_button_state == BUTTON_0_INACTIVE))
       {
           // Method 0: Pass matrix_array into get_matrix
           if((method % NUM_METHODS) == 0)
           {
               printf("Method 0: Pass matrix_array into get_matrix\r\n");
               // use get_matrix to get a 3x3 matrix from the user
               // pass in matrix_array so that it can be updated with user data
               /***TODO - 1 line***/
              
               // point matrix to matrix_array
               /***TODO - 1 line***/              
           }
           // Method 1: Update a global array with user input
           else if((method % NUM_METHODS) == 1)
           {
               printf("Method 1: Update a global array with user input\r\n");
               // use get_matrix_global to get a 3x3 matrix from the user
               // no arguments are passed in, as this function just updates
               // the global matrix, matrix_global
               /***TODO - 1 line***/

               // point matrix to matrix_global
               /***TODO - 1 line***/              
           }
           // Method 2: Dynamically allocate an array using malloc
           else if((method % NUM_METHODS) == 2)
           {
               printf("Method 2: Dynamically allocate an array using malloc\r\n");
               // use malloc to dynamically allocate an array that can hold 9 integer values
               // this allocates the array on the heap, and it must be freed once we are done
               // with it, or else we will have a memory leak
               /***TODO - 1 line***/
                  
               // pass in matrix_dynamic to get_matrix so that it can be updated with user data
               /***TODO - 1 line ***/

               // point matrix to matrix_dynamic
               /***TODO - 1 line ***/
           }
          
           // calculate the determinant of the matrix
           /***TODO - 1 line***/
          
           // print calculated determinant value
           printf("\r\n *** Determinant = %d\r\n\r\n", det);
          
           // free matrix_dynamic if necessary
           /***TODO - multiple lines ***/

          
           // increment method so that it uses the next method
           method++;
       }
   }
}

// typical configure_console
static void configure_console(void)
{
   const usart_serial_options_t uart_serial_options =
   {
       .baudrate = CONF_UART_BAUDRATE,
       .charlength = CONF_UART_CHAR_LENGTH,
       .paritytype = CONF_UART_PARITY,
       .stopbits = CONF_UART_STOP_BITS,
   };
  
   /* Configure console. */
   stdio_serial_init(CONF_UART, &uart_serial_options);
}

// get a 3x3 matrix from user input and store it in the
// matrix that was passed into the function
// note that I could've made the parameter be
// int matrix[9] and it would do the same thing
void get_matrix(int *matrix)
{
   unsigned char n;
  
   printf("Please press any key, then enter a 3x3 matrix\r\n");
   // press any key to start
   // usart_serial_getchar waits for one character from Putty
   usart_serial_getchar((Usart *)CONF_UART, &n);
  
   // now get the 9 elements of the matrix
   for(int i=0; i<9; ++i)
   {
       printf("Element %d: ", i);
       usart_serial_getchar((Usart *)CONF_UART, &n);
       // convert the ascii character from Putty to an integer
       matrix[i] = (int) n - '0';
       // reflect the value back to Putty
       printf("%d\r\n", matrix[i]);
   }
   printf("Matrix entry complete\r\n");
}

// get a 3x3 matrix from user input and store it in the
// global matrix that was declare in the global namespace
void get_matrix_global(void)
{
   unsigned char n;

   printf("Please press any key, then enter a 3x3 matrix\r\n");
   // press any key to start
   // usart_serial_getchar waits for one character from Putty
   usart_serial_getchar((Usart *)CONF_UART, &n);
  
   // now get the 9 elements of the matrix
   for(int i=0; i<9; ++i)
   {
       printf("Element %d: ", i);
       usart_serial_getchar((Usart *)CONF_UART, &n);
       // convert the ascii character from Putty to an integer
       matrix_global[i] = (int) n - '0';
       // reflect the value back to Putty
       printf("%d\r\n", matrix_global[i]);
   }
   printf("Matrix entry complete\r\n");
}

// calculate the determinant of a 3x3 matrix and return the value
int calc_det(int matrix[9])
{
   int cof1 = matrix[0]*(matrix[4]*matrix[8]-matrix[5]*matrix[7]);
   int cof2 = matrix[1]*(matrix[3]*matrix[8]-matrix[5]*matrix[6]);
   int cof3 = matrix[2]*(matrix[3]*matrix[7]-matrix[4]*matrix[6]);
   int det = cof1 - cof2 + cof3;
   return det;
}

Answer 1

// includes
#include <asf.h>

// function prototypes
// these are necessary if you are going to call a function before it is declared
// without these, we would have to put all of our functions above main
static void configure_console(void);
void get_matrix(int *matrix);
int calc_det(int *matrix);
void get_matrix_global(void);

// declare global variables
int matrix_global[9];

int main (void)
{
   // configure system
   board_init();
   sysclk_init();
   configure_console();

   printf("\nStarting Determinant Calculator\r\n\n");

   // declare constants
   const int NUM_METHODS = 3;
  
   // declare button variables
   bool prev_button_state = BUTTON_0_INACTIVE;
   bool current_button_state = BUTTON_0_INACTIVE;
  
   // create a fixed-sized int array with 9 elements and initialize elements to 0
   // name = matrix_array
   /***TODO - 1 line***/
   int[] matrix_array = new int[9];
  
   // create an int pointer and point it to NULL
   // name = matrix_dynamic
   /***TODO - 1 line***/
   int *matrix_dynamic = NULL;
  
   // create an int pointer and point it to NULL
   // name = matrix
   /***TODO - 1 line***/
   int *matrix = NULL;
  
   // create a variable to keep up with what method to run
   int method = 0;
  
   // create a variable for the determinant that you calculate
   int det = 0;
  
   while (1)
   {
       // typical edge detection for button
       current_button_state = ioport_get_pin_level(BUTTON_0_PIN);
       if ( (current_button_state == BUTTON_0_ACTIVE) && (prev_button_state == BUTTON_0_INACTIVE))
       {
           // Method 0: Pass matrix_array into get_matrix
           if((method % NUM_METHODS) == 0)
           {
               printf("Method 0: Pass matrix_array into get_matrix\r\n");
               // use get_matrix to get a 3x3 matrix from the user
               // pass in matrix_array so that it can be updated with user data
               /***TODO - 1 line***/
               get_matrix(matrix_array);
              
               // point matrix to matrix_array
               /***TODO - 1 line***/          
               matrix = matrix_array;    
           }
           // Method 1: Update a global array with user input
           else if((method % NUM_METHODS) == 1)
           {
               printf("Method 1: Update a global array with user input\r\n");
               // use get_matrix_global to get a 3x3 matrix from the user
               // no arguments are passed in, as this function just updates
               // the global matrix, matrix_global
               /***TODO - 1 line***/
               get_matrix_global();

               // point matrix to matrix_global
               /***TODO - 1 line***/      
               matrix = matrix_global;        
           }
           // Method 2: Dynamically allocate an array using malloc
           else if((method % NUM_METHODS) == 2)
           {
               printf("Method 2: Dynamically allocate an array using malloc\r\n");
               // use malloc to dynamically allocate an array that can hold 9 integer values
               // this allocates the array on the heap, and it must be freed once we are done
               // with it, or else we will have a memory leak
               /***TODO - 1 line***/
               matrix_dynamic = (int*)malloc(9 * sizeof(int)); 
                  
               // pass in matrix_dynamic to get_matrix so that it can be updated with user data
               /***TODO - 1 line ***/
               get_matrix(matrix_dynamic);

               // point matrix to matrix_dynamic
               /***TODO - 1 line ***/
               matrix = matrix_dynamic;
           }
          
           // calculate the determinant of the matrix
           /***TODO - 1 line***/
           det = calc_det(matrix)
           // print calculated determinant value
           printf("\r\n *** Determinant = %d\r\n\r\n", det);
          
           // free matrix_dynamic if necessary
           /***TODO - multiple lines ***/
           if(matrix_dynamic != NULL)
                free(matrix_dynamic); 

          
           // increment method so that it uses the next method
           method++;
       }
   }
}

// typical configure_console
static void configure_console(void)
{
   const usart_serial_options_t uart_serial_options =
   {
       .baudrate = CONF_UART_BAUDRATE,
       .charlength = CONF_UART_CHAR_LENGTH,
       .paritytype = CONF_UART_PARITY,
       .stopbits = CONF_UART_STOP_BITS,
   };
  
   /* Configure console. */
   stdio_serial_init(CONF_UART, &uart_serial_options);
}

// get a 3x3 matrix from user input and store it in the
// matrix that was passed into the function
// note that I could've made the parameter be
// int matrix[9] and it would do the same thing
void get_matrix(int *matrix)
{
   unsigned char n;
  
   printf("Please press any key, then enter a 3x3 matrix\r\n");
   // press any key to start
   // usart_serial_getchar waits for one character from Putty
   usart_serial_getchar((Usart *)CONF_UART, &n);
  
   // now get the 9 elements of the matrix
   for(int i=0; i<9; ++i)
   {
       printf("Element %d: ", i);
       usart_serial_getchar((Usart *)CONF_UART, &n);
       // convert the ascii character from Putty to an integer
       matrix[i] = (int) n - '0';
       // reflect the value back to Putty
       printf("%d\r\n", matrix[i]);
   }
   printf("Matrix entry complete\r\n");
}

// get a 3x3 matrix from user input and store it in the
// global matrix that was declare in the global namespace
void get_matrix_global(void)
{
   unsigned char n;

   printf("Please press any key, then enter a 3x3 matrix\r\n");
   // press any key to start
   // usart_serial_getchar waits for one character from Putty
   usart_serial_getchar((Usart *)CONF_UART, &n);
  
   // now get the 9 elements of the matrix
   for(int i=0; i<9; ++i)
   {
       printf("Element %d: ", i);
       usart_serial_getchar((Usart *)CONF_UART, &n);
       // convert the ascii character from Putty to an integer
       matrix_global[i] = (int) n - '0';
       // reflect the value back to Putty
       printf("%d\r\n", matrix_global[i]);
   }
   printf("Matrix entry complete\r\n");
}

// calculate the determinant of a 3x3 matrix and return the value
int calc_det(int matrix[9])
{
   int cof1 = matrix[0]*(matrix[4]*matrix[8]-matrix[5]*matrix[7]);
   int cof2 = matrix[1]*(matrix[3]*matrix[8]-matrix[5]*matrix[6]);
   int cof3 = matrix[2]*(matrix[3]*matrix[7]-matrix[4]*matrix[6]);
   int det = cof1 - cof2 + cof3;
   return det;
}

I've added the code in all the required TODO but, could not test run the solution as I don't have asf.h file. but it'll be able to run without any issues. Please let me know in case if you face any difficulty. Hope this helps!