/*
 * pointref.cpp
 *
 *  Created on: 03.12.2013
 *      Author: trifon
 */

#include <iostream>
using namespace std;

void test_string() {
	char s[] = "Hello, world!";
	char* p = s;
	while (*p) {
		cout << *p << ' ';
		p++;
	}
	do {
		p--;
		cout << *p;
	} while (p != s);
	// p == s
}

void test_pointers() {
	int *pi;
	double *pd = NULL;
	double d = 1.23;
	double *qd = &d;
	// !!! double *qd2 = &qd;
	double **qqd = &qd;
	// !!! double **qqd2 = &d;

	// !!!! pi = (int*)&pi;

	cout << pi << ' ' << pd << ' ' << d << ' ' << qd
			   << ' ' << qqd << endl;

	int x = 5, *p = &x, *q = p, y = *p + 2;
	// !!! cout << *p++ << endl;
	cout << (*p)++ << endl;
	cout << x << ' ' << y << ' ' << &x << ' ' << &y << endl;
	// !!! cout << *x << ' ' << *y << endl;
	cout << p << ' ' << q << ' ' << *p << ' ' << *q << endl;
	cout << &p << ' ' << &q << endl;

}

void print_array(int a[], int n) {
	for(int i = 0; i < n; i++)
		cout << a[i] << ' ';
	cout << endl;
}

void test_sizes() {
	cout << "char: " << sizeof(char) << endl;
	cout << "int: " << sizeof(int) << endl;
	cout << "long: " << sizeof(long) << endl;
	cout << "float: " << sizeof(float) << endl;
	cout << "double: " << sizeof(double) << endl;
	int a[5] = { 1, 2, 3, 4, 5 };
	int* p = a;
	char s[] = "Hello, world!";
	char* q = s;
	cout << "a: " << sizeof(a) << endl;
	cout << "p: " << sizeof(p) << endl;
	cout << "s: " << sizeof(s) << endl;
	cout << "q: " << sizeof(q) << endl;
	cout << p << ' ' << (p + 5) << endl;
	cout << (long)q << ' ' << (long)(q + 5) << endl;
	cout << 2[a] << ' ' << a[2] << endl;
	cout << s << ' ' << s + 2 << endl;
	print_array(a, 5);
	print_array(a + 2, 3);
	int const* r = a;
	r++;
	cout << *r << endl;
	// !!! *r = 15;
	// !!! int* r2 = r;
	// !!! *r2 = 15;
	int *r2 = (int*)r;
	*r2 = 15;
	print_array(a, 5);
	const int N = 5;
	// !!! p = &N;
	// !!! *p = 30;
	r = &N;
	cout << *r << endl;
	char *s2 = "Hi C++!"; // указател, който сочи към някаква ??? памет, съдържаща низа
	char s3[] = "Hi C++!"; // масив, който съдържа низа
	// !!! s2[1] = 'o';
	int M[N][N];
	int element = 0;
	for(int i = 0; i < N; i++)
		for(int j = 0; j < N; j++ )
			M[i][j] = element++;
	for(int i = 0; i < N; i++)
		print_array(M[i]+i, N-i);
}

void test_voidstar() {
	int i = 10;
	double d = 1.23;
	char c = 'X';
	bool b = true;

	void* p;
	p = &i;
	p = &d;
	p = &c;
	p = &b;
	p = &p;
	p = &d;
	// !!! p = &c;

	// !!! cout << *p << endl;

	// да приемем, че знаем отнякъде, че p сочи към bool
	// bool* pb = (bool*)p;
	// cout << *pb << endl;

	// да приемем, че знаем отнякъде, че p сочи към double
	double* pd = (double*)p;
	cout << *pd << endl;

}

void test_reference() {
	int x = 5;
	int& y = x;
	cout << x << ' ' << y << endl;
	y = 6;
	cout << x << ' ' << y << endl;
	x = 7;
	cout << x << ' ' << y << endl;

	// !!! int& z;
	// !!! int * const p;
	// !!! int const N;
	int z, &t = z, &u = x;

	int const* p = &x;
	// !!! *p = 10;
	// !!! int& a = *p;
	// !!! a = 10;
	int const& b = *p;

	int *const px = &x;
	*px = 10;
	y = 10;

}

void f(int x) {
	x++;
	cout << "f: " << x << endl;
}

void g(int* p) {
	(*p)++;
	cout << "g: " << *p << endl;
}

void swap(int* p, int* q) {
	int tmp = *p; *p = *q; *q = tmp;
}

int main() {
	// test_pointers();
	// test_string();
	// test_sizes();
	// test_voidstar();
	// test_reference();
	int x = 20, y = 10;
	f(y);
	cout << y << endl;
	g(&y);
	cout << y << endl;
	swap(&x, &y);
	cout << x << ' ' << y << endl;
	return 0;
}