/*
 * functions.cpp
 *
 *  Created on: 06.12.2012
 *      Author: trifon
 */

#include <iostream>
#include <cmath>
#include <cstring>
#include "functions.h"
using namespace std;

const int N = 5;

double triarea(double x1, double y1, double x2, double y2,
				 double x3, double y3)
{
	double a = distance(x1, y1, x2, y2);
	double b = distance(x2, y2, x3, y3);
	double c = distance(x1, y1, x3, y3);
	x1 = x1 * 7;
	x3 = x3 / 2;
	return heron(a, b, c);
}

double distance(double x1, double y1, double x2, double y2)
{
	return sqrt(sqr(x2-x1) + sqr(y2-y1));
}

inline double sqr(double a) { return a*a; }

double heron(double a, double b, double c)
{
	double p = (a+b+c)/2;
	return sqrt(p*(p-a)*(p-b)*(p-c));
}

void readPoint(int n, double* px, double* py)
{
	cout << "(x" << n;
	cout << ",y" << n;
	cout << ") = ";
	cin >> *px >> *py;
}


int main1() {
	double x[3], y[3];
	/*
	readPoint(1, &x[0], &y[0]);
	readPoint(2, &x[1], &y[1]);
	readPoint(3, &x[2], &y[2]);
	 */
	/*
	readPoint(1, x, y);
	readPoint(2, x+1, y+1);
	readPoint(3, x+2, y+2);
	*/
	for(int i = 0; i < 3; i++)
		readPoint(i+1, x+i, y+i);

	cout << "Лицето е " << triarea(x[0], y[0], x[1], y[1], x[2], y[2])
			<< endl;
	return 0;
}

int f(int x) {
	static int n = 0;
	return x + n++;
}

int g()
{
	int n;
	cin >> n;
	return n+1;
}

void swap(short* px, short* py)
{
	cout << "Разменяме две малки цели числа!\n";
	short tmp = *px;
	*px = *py;
	*py = tmp;
}

void swap(int* px, int* py)
{
	cout << "Разменяме две цели числа!\n";
	int tmp = *px;
	*px = *py;
	*py = tmp;
	// безсмислено:
	// px = py;
	// py = &tmp;
}

void swap(int* px, int* py, int* pz)
{
	cout << "Разменяме три цели числа!\n";
	int tmp = *px;
	*px = *py;
	*py = *pz;
	*pz = tmp;
}

void swap(double* pa, double* pb)
{
	cout << "Разменяме две дробни числа!\n";
	double tmp = *pa;
	*pa = *pb;
	*pb = tmp;
}


void swap(int& x, int& y)
{
	int tmp = x;
	x = y;
	y = tmp;
}

int main2() {
	cout << f(0) << endl;
	cout << f(0) << endl;
	cout << f(0) << endl;
	cout << g() << g() << g() << endl;
}

void copy2(char* dest, char const* source)
{
	strcpy(dest, source);
	strcat(dest, source);
}


int main3()
{
	int a, b, c;
	cin >> a >> b >> c;
	swap(&a,&b);
	swap(a,b);
	// !!! swapr(2,3);
	// !!! int &x = 2;
	// !!! int &y = 3;
	// !!! swapr(a+1,b+1);
	// !!! swap(&2, &3);
	cout << a << ' ' << b << endl;
	char s1[] = "Hello, world!";
	char s2[100] = "";
	copy2(s2, s1);
	cout << s2 << endl;
	copy2(s2, "abc");
	cout << s2 << endl;
	// !!! copy2("abc", s1);
	// char const* source = "abc";
	// !!! char* dest = "abc";
	swap(&a, &b, &c);

	// !!! int x;
	// !!! double x;
	cout << a << ' ' << b << ' ' << c << endl;

	double d = 1.2, e = 2.3;
	swap(&d, &e);
	cout << d << ' ' << e << endl;
}

void readArray(int arr[], int n, char const* name)
{
	for(int i = 0; i < n; i++)
	{
		cout << name << "[" << i << "] = ";
		cin >> arr[i];
	}
}

void writeArray(int arr[], int n, char const* name)
{
	for(int i = 0; i < n; i++)
		cout << name << "[" << i << "] = " << arr[i] << endl;
}

int search(int arr[], int n, int x)
{
	int i = 0;
	while (i < n && arr[i] != x)
		i++;
	/*
	if (i < n)
		return true;
	return false;
	*/
	if (i == n)
		return -1;
	return i;
}

bool equal(char const* s1, char const* s2) {
	return strcmp(s1, s2) == 0;
}

void findMinMax(int arr[], int n, int& min, int& max)
{
	min = max = arr[0];
	for(int i = 1; i < n; i++)
	{
		if (arr[i] < min)
			min = arr[i];
		if (arr[i] > max)
			max = arr[i];
	}
}

void writeMatrix(int matrix[][N], int n, int m)
{
	for(int i = 0; i < n; i++)
	{
		for(int j = 0; j < m; j++)
			cout << matrix[i][j] << '\t';
		cout << endl;
	}
}

int main4()
{
	int a[N] = { 0 }, b[N] = {0};
	readArray(a, N, "a");
	readArray(b, N, "b");
	// readArray(a + 2, 3, "a");
	writeArray(a, N, "a");
	int x;
	cout << "x = ";cin >> x;
	cout << search(a, N, x) << ' ' <<
			search(b, N, x) << endl;
	cout << equal("abc","abc") << endl;
	int mina, maxa, minb, maxb;
	findMinMax(a, N, mina, maxa);
	findMinMax(b, N, minb, maxb);
	cout << mina << ' ' << maxa << endl;
	cout << minb << ' ' << maxb << endl;
}

const int NWORDS = 20, WORDSIZE = 100;

/*
 * Прочита масив от низове, максимум NWORDS низа от по
 * максимум WORDSIZE символа.
 * Връща броя на прочетените низове
 */
int readWords(char w[][WORDSIZE])
{
	int i = 0;
	do
	{
		cout << "Въведете дума " << i+1 << " ";
		cin.getline(w[i], WORDSIZE);
		i++;
	} while (i < NWORDS && w[i-1][0] != '\0');
	// i == NWORDS || w[i-1][0] == '\0'
	return i-1;
}

int searchWord(char (*w)[WORDSIZE], int nwords, char const* word)
{
	int i = 0;
	while (i < nwords && !equal(w[i], word))
		i++;
	// i == nwords || equal(w[i], word)
	if (i == nwords)
		return -1;
	return i;
}


int main5()
{
	int m[N][N] = { { 1, 2, 3, 4, 5},
					 { 6, 7, 8, 9, 10},
					 { 11, 12, 13, 14, 15},
					 { 16, 17, 18, 19, 20},
					 { 21, 22, 23, 24, 25} };
//	writeMatrix(m + 2, 3, 3);
	writeMatrix(m, N, N);

	char words[NWORDS][WORDSIZE];
	int nwords = readWords(words);
	cout << nwords << endl;
	cout << searchWord(words, nwords, "Hello") << endl;
}

int* wrong(int y)
{
	int x = y + 2;
	return &x;
}

int main6()
{
	int* p = wrong(2);
	cout << *p << endl;
	*p = 10;
	wrong(20);
	cout << *p << endl;
}

int* pointMax(int* p, int* q) {
	if (*p > *q)
		return p;
	return q;
}

int& middle( int& x, int& y, int& z) {
	if (x <= y && y <= z || z <= y && y <= x)
		return y;
	if (y <= z && z <= x || x <= z && z <= y)
		return z;
	return x;
}

const int MAX = 1000;
// int x;

// !!!! int[10] f();

// double a[][MAX] = {0}, b[][MAX] = {0};

void multiplyMatrices(double a[][MAX], double b[][MAX],
		                 double c[][MAX],
		                 int n, int m, int p)
{
	for(int i = 0; i < n; i++)
		for(int j = 0; j < p; j++)
		{
			c[i][j] = 0;
			for(int k = 0; k < m; k++)
				c[i][j] += a[i][k] * b[k][j];
		}
}

int main7()
{
	int a = 2, b = 5, c = 3;
	int* p = pointMax(&a, &b);
	cout << *p << endl;
	//!!!! *p-- <--> *(p--);
	(*p)--;
	cout << b << endl;
	// middle(a,b,c) = 8;
	int& m = middle(a,b,c);
	m = 8;
	cout << c << endl;
}

// strchr
char const* my_strchr(char const* s, char c)
{
	char const* p = s;
	while (*p != '\0' && *p != c)
		p++;
	// *p == '\0' || *p == c
	return p;
}

char const* my_strdiff(char const* s1, char const* s2)
{
	char const *p = s1, *q = s2;
	while (*p == *q && *p != '\0' && *q != '\0')
	{
		p++; q++;
	}
	// *p != *q || *p == '\0' || *q == '\0'
	return p;
}

int main()
{
	char str[] = "Hello, world!";
	cout << my_strchr(str, 'l') << endl;
	cout << my_strchr(str, 't') << endl;
	cout << my_strdiff(str, "Help me!") << endl;
}