#include<stdio.h> // For printf
#include<stdlib.h> // For malloc
#include"er_in2060.h" // header fileFrim

int main(){
  /********** Part 1: Variables **********/

  // In C variables are weakly typed
  int a = 4;
  char b = 'h';

  printf("4 + h is: %i\n", a+b);

  /********** Part 2: If/else Statements **********/

  if(b > a){
    a += 4;
  }
  else{
    a += 2;
  }

  printf("%i\n", a);

  /********** Part 3: Pointers **********/

  int x = 8;
  int y = 3;

  printf("Content (x:y): %d : %d\n", x, y);
  printf("Address (&x:&y): %p : %p\n", &x, &y);

  int* z;
  z = &x;

  printf("Pointer to an integer (z): %p\n", z); // z hold the address of x
  printf("Pointer to a pointer (&z): %p\n", &z); //&z hold the address of z
  printf("Derreferenced pointer (*z): %d\n", *z); // *z is the value of x
  printf("(*(&z)): %p\n", *(&z)); // *(&z) is the value of z, which is the address of x
  printf("(&(*z)): %p\n", &(*z)); // &(*z) is the address of x

  int* my_pointer = NULL;

  printf("Null pointer: %p\n", my_pointer);

  if (my_pointer == NULL) {
    printf("'my_pointer' is empty\n");
	}
 

  int* pointer = malloc(sizeof(int)*1);

  pointer[0] = 3;

  printf("A pointer: %x\n", pointer);

  free(pointer);
  
  /********** Part 4: Strings and memory allocation **********/

  // Strings are represented by placing several chars after each other in memory
  // Memory must be allocated for a string
  char* string = "Hello!";
  char* string_2 = malloc(sizeof(char)*7);
  char* start_string_2 = string_2;// save the start of the memory block

  string_2[0] = 'H';
  string_2[1] = 'e';
  string_2[2] = 'l';
  string_2[3] = 'l';
  string_2[4] = 'o';
  string_2[5] = '!';
  string_2[6] = 0;

  printf("%s\n", string_2);

  // Allocate a 3x3 matrix
  int* matrix_data = malloc(sizeof(int)*3*3);
  int** matrix = malloc(sizeof(int*)*3);
  for(int i = 0; i < 3; i++){
    matrix[i] = &matrix_data[i*3];
  }
  //Indexes
  int x1 = 0;
  int y1 = 2;
 //Assignation
  matrix[x1][y1] = 128;
  //Access through indexes
  printf("Matrise [x1][y1] = %d\n", matrix[x1][y1]);
  //Check strukt.c example

  /********** Part 5: Loops **********/

  for(int i = 0; i < 6; i++){
    printf("%i\n", i);
  }

  while(*string_2){
    printf("%c\n", string_2[0]);
    string_2 += 1; //pointer is being moved
  }

  /********** Part 6: Functions and header files **********/
  printf("Er det IN2060? %s\n", er_IN2060("IN2060"));

  free(start_string_2);//We must free from the begining of the allocated memory block
}