insert code in all TODO part, it's about pointer. atmel studio7.0. this should be able to run without utilities.h

// includes
#include

// function prototypes
// these are necessary if you are going to call a function beforeit is declared
// without these, we would have to put all of our functions abovemain
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 DeterminantCalculator\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 andinitialize 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 torun
   int method = 0;
  
   // create a variable for the determinant that youcalculate
   int det = 0;
  
   while (1)
   {
       // typical edge detection forbutton
       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 intoget_matrix\r\n\");
              // use get_matrix to get a 3x3 matrix from theuser
              // pass in matrix_array so that it can beupdated 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 withuser input\r\n\");
              // use get_matrix_global to get a 3x3 matrixfrom the user
              // no arguments are passed in, as this functionjust 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 arrayusing malloc\r\n\");
              // use malloc to dynamically allocate an arraythat can hold 9 integer values
              // this allocates the array on the heap, and itmust be freed once we are done
              // with it, or else we will have a memoryleak
              /***TODO - 1 line***/
                 
              // pass in matrix_dynamic to get_matrix so thatit can be updated with user data
              /***TODO - 1 line ***/

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

          
           // incrementmethod 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 3x3matrix\r\n\");
   // press any key to start
   // usart_serial_getchar waits for one character fromPutty
   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 fromPutty to an integer
       matrix[i] = (int) n - '0';
       // reflect the value back toPutty
       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 3x3matrix\r\n\");
   // press any key to start
   // usart_serial_getchar waits for one character fromPutty
   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 fromPutty to an integer
       matrix_global[i] = (int) n -'0';
       // reflect the value back toPutty
       printf(\"%d\r\n\",matrix_global[i]);
   }
   printf(\"Matrix entry complete\r\n\");
}

// calculate the determinant of a 3x3 matrix and return thevalue
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;
}