/* COMPILE: g++ -std=c++98 -Wall -Wextra -O start.cpp
*/

// C++ libraries: 
#include <iostream> 
#include <string>   // c++ string class

/* New names for C libraries: <cmath> <cctype> <cstdlib> <cstdio> <cstring> */

/* namespace: use std the most */

/* using declarations specify the scope - simplify use */
using std::cout;	using std::cin;
using std::endl;	using std::string;

/* can declare using entire namespace:
using namespace std;
*/

void swap1(int, int);       // pass by value, doesn't work
void swap2(int *, int *);   // pass by reference with pointers
void swap3(int &, int &);	// pass by reference w/aliasing

int main()
{
	std::cout << "Hello World";
	std::cout << std::endl;

	int age;
	std::cout << "what is your age? ";
	std::cin >> age;
	std::cout << "enjoy the heat, " << age << " year-old" << std::endl;

	cout << "woohoo" << endl;

/* WORKING WITH OBJECTS
*/
	string s1 = "blah";
	string name;

	string s2("blahblah");	// constructor call
	string s3(s2);		// copy constructor
	string spaces(10, ' '); // ten spaces

	cout << "enter name: ";
	cin >> name;		// stops at whitespace

	cout << "enter text: ";
	string text;
	getline(cin, text);	// read to end of line, including spaces

	s3 = s1 + ' ' + s2;  // "blah blahblah"
	text += name;
	
	s1 = s2;		// deep copy

	cout << s1.length() << " " << s1.size() << endl;
	cout << s1.capacity() << endl;
	cout << s3.substr(3, 5) << endl; // h bla

	if (s1.compare(s2) < 0)
		cout << "s1 < s2" << endl;

	if (s1 < s2) // < > <= >= == != 
	  cout << "s1 < s2" << endl;
	
	s1 = "cat";
	cout << s1.at(1) << endl;  // 'a'  - does range checking
	s1.at(1) = 'o';
	cout << s1 << " "  << s1[1] << endl;  // cot o
	s1[0] = 'C';
	

/* WORKING WITH PRIMITIVES
*/
	int num1, num2 = 6;
	bool flag = true;	// any non-zero is true, zero is false
	double d1 = 13.55;

	num1 = (int) d1;
	num1 = int(d1);
    num1 = static_cast<int>(d1);

	swap1(num1, num2);  // call by value

	cout << "enter 2 ints and 1 double: ";
	cin >> num1 >> num2 >> d1;
	swap2(&num1, &num2);	// pass the address to pointers
	cout << num1 << " " << num2 << endl;

	cout << "enter 2 ints and 1 double: ";
	cin >> num1 >> num2 >> d1;
	swap3(num1, num2);	// pass to aliases
	cout << num1 << " " << num2 << endl;

	int &num3 = num1;	// num3 is alias for num1
	num3 = 234;
	cout << num1 << endl; // 234

	cout << "enter pairs of grades and max points:" << endl;
	int grade, maxp;
	int totalgrade = 0, totalmax = 0;

	while (cin >> grade >> maxp) {
		totalgrade += grade;
		totalmax += maxp;
	}
	double avg = (double) totalgrade / totalmax * 100;
	cout << "homework average is " << avg << endl;

	char ch;
	cin.get(ch);	// read next character

/* auto buffer flushing: 
	at end of line (endl, '\n')	
	if buffer full
	when read encountered
*/
	cout << std::flush;
}

void swap1(int a, int b)	// pass by value, doesn't work
{
	int temp = a;
	a = b;
	b = temp;
}

void swap2(int *ap, int *bp)  	// pass by reference with pointers
{
	int temp = *ap;
	*ap = *bp;
	*bp = temp;
}

void swap3(int &aa, int &ba)	// pass by reference w/aliasing
{
	int temp = aa;
	aa = ba;
	ba = temp;
}