// C programming tutorial, Nov 16 - Pouya Larjani

// Compile with: gcc nov-16.c

// Including files
#include <stdio.h>

// Macros
#define MAX_INT_WHATEVER 42
#define SQR(x) x*x

// Structures (records)
struct pair_s {
    int a;
    double b;
};

// Defining types
typedef struct pair_s pair;
/*    void (in C) = unit (in OCaml)
      double  (C) = float   (OCaml)  (64-bit floating point)
      float   (C) = 32-bit floating point number, no equivalent in OCaml
*/

// Prototypes
void print_something(pair); // print_something : pair -> void

// Main function, only code inside here will be run
int main()
{
    // Printing (uses stdio)
    printf("Hello, World!\n\n");

    // Defining variables. Explicit typing, no inference
    pair p1;
    // Assigning to record fields
    p1.a = 42;
    p1.b = 68.99;
    // Defining variable and initializing inline
    pair p2 = {11,22.22};
    // Calling functions
    print_something(p1);
    print_something(p2);

    // Random gotcha's with macros!
    printf("SQR(2+3) = %d\n", SQR(2+3)); // = 2+3*2+3 = 11, not 25!!
    printf("SQR((2+3)) = %d\n", SQR((2+3))); // = (2+3)*(2+3) = 25

    // Pointers and (de/)referencing
    int *i;   // i: int ref
    int num = 42; // num : int
    
    i = &num; // i := num
    printf("The de-referenced number is: %d\n", *i); // !i
    
    // By ANSI standards main() is supposed to return an int.
    // Being void is fine but it generates a warning
    return 0;
}

// Defining functions
void print_something(pair i)
{
    // Format string: %d or %i = int, %f = float and double, %s = string
    printf("The pair is: (%d, %f)\n", i.a, i.b);
}