// file: lecture_10/example.cc
//

// local include files
//
#include "example.h"

// method: main
//
// main program starts here
//
int main(int argc, char** argv) {

  // declare a character string
  //
  char str2[] = "Alex";
  fprintf(stdout, "(null terminated)str2 = %s\n", str2);
  char str[4]; str[0]='A';str[1]='l';str[2]='e';str[3]='x';

  fprintf(stdout, "str[0] = %c (%d)\n", str[0], str[0]);
  fprintf(stdout, "str[1] = %c (%d)\n", str[1], str[1]);
  fprintf(stdout, "str[2] = %c (%d)\n", str[2], str[2]);
  fprintf(stdout, "str[3] = %c (%d)\n", str[3], str[3]);
  fprintf(stdout, "str[4] = %c (%d)\n", str[4], str[4]);

  // note that argv[1] is a character string
  //
  fprintf(stdout, "argv[1] = %s\n", argv[1]);
  
  // let's declare a floating-point array
  //
  long N = 3;
  float x[N];
  //  float x[atoi(argv[2])];
  x[0] = 1.0;
  x[1] = 2.0;
  x[2] = 3.0;

  fprintf(stdout, "x[0] = %f (%f)\n", x[0], x[0]);
  fprintf(stdout, "x[1] = %f (%f)\n", x[1], x[1]);
  fprintf(stdout, "x[2] = %f (%f)\n", x[2], x[2]);

  // use a more flexible format for declaring an array
  //
  float y[] = {1.0, 2.0, 3.0};
  fprintf(stdout, "y[0] = %f (%f)\n", y[0], y[0]);
  fprintf(stdout, "y[1] = %f (%f)\n", y[1], y[1]);
  fprintf(stdout, "y[2] = %f (%f)\n", y[2], y[2]);
  
  // arrays can be multidimensional
  //
  float z[2][9][27][99][35];
  z[0][0][0][0][0] = 0.0;
  z[0][0][0][0][1] = 27.0;
  z[0][0][0][0][34] = 99.0;
  fprintf(stdout, "z[0][0][0][0][0] = %f\n", z[0][0][0][0][0]);
  fprintf(stdout, "z[0][0][0][0][1] = %f\n", z[0][0][0][0][1]);
  fprintf(stdout, "z[0][0][0][0][34] = %f\n", z[0][0][0][0][34]);

  // introduce a pointer
  //
  fprintf(stdout, "---- pointers ----\n");
  float joe = 27.2727;
  float* ptr = &joe;
  fprintf(stdout, "joe = %f\n", joe);
  fprintf(stdout, "the memory location for joe is %p (%u) (%f)\n", ptr, ptr, *ptr);
  fprintf(stdout, "the memory location for joe is %p (%u) (%ld)\n", ptr, ptr, (long)*ptr);

  // interpret a float as an int
  //
  int* iptr = (int*)ptr;
  fprintf(stdout, "the memory location for joe is %p (%u) (%ld)\n", iptr, iptr, *iptr);

  // increment a pointer
  //
  float yy[] = {1.0, 2.0, 3.0, 4.0, 5.0};
  float* zz = yy;
  fprintf(stdout, "y[0] = %f\n", *zz);
  zz++;
  fprintf(stdout, "y[1] = %f\n", *zz);
  zz++;
  fprintf(stdout, "y[2] = %f\n", *zz);
  
  // create a multidimensional array
  //
  float yyy[2][3];
  float* zzz = (float*)yyy;
  yyy[0][0] = 1.0;  yyy[0][1] = 2.0;  yyy[0][2] = 3.0;
  yyy[1][0] = 4.0;  yyy[1][1] = 5.0;  yyy[1][2] = 6.0;

  for (long i = 0; i < 2; i++) {
    for (long j = 0; j < 3; j++) {
      fprintf(stdout, "%f (%f) ", yyy[i][j], *zzz++);
    }
    fprintf(stdout, "\n");
  }

  // explain a pointer to a pointer
  //
  fprintf(stdout, "===== argv =====\n");
  fprintf(stdout, "argv = %u\n", argv);
  fprintf(stdout, "argv[0] = %s (%u)\n", argv[0], argv[0]);
  fprintf(stdout, "argv[1] = %s (%u)\n", argv[1], argv[1]);
  fprintf(stdout, "argv[2] = %s (%u)\n", argv[2], argv[2]);

  fprintf(stdout, "=====\n");
  fprintf(stdout, "argv[0] = %s\n", argv[0]);
  fprintf(stdout, "argv[0][0] = %c\n", argv[0][0]);
  fprintf(stdout, "argv[0][1] = %c\n", argv[0][1]);
  
  // we can use pointers with functions
  //
  float* myptr = new float[10];
  myptr[0] = 27.0;
  fprintf(stdout, "BEFORE: %f\n", *myptr);
  bool status = myfunct(myptr);
  fprintf(stdout, "AFTER: %f\n", *myptr);
  delete [] myptr;

  // allocate an array
  //
  float* jordan = new float[99];
  delete [] jordan;

  // to review: char's use null-terminated strings
  //
  char* aaa = (char*)"Joe"; // allocates 3+null=4 characters
  char ccc[] = "Joe"; // allocates 3 characters
  float bbb[] = {1.0, 2.0, 3.0}; // allocates 3 floats = 3x4 = 12 bytes
  
  // exit gracefully
  //
  exit(0);
}

bool myfunct(float* x) {
  *x = 99.0; // changes the value of x in the calling program because it is a pointer
  return true;
}