/********************************************************************
 * Andrei Florea - CST 116 - Chapter 9 - Debugging & Functions
 *
 * Chapter 9 Questions & Answers (it didn't specify which questions, so I'm assuming all?)
 *  How does a computer know where to go back to?
 *      - It knows because of a parameter that is called the return address, which lets the computer know
 *      where to go back to after executing the function.
 *
 *  How does it maintain the state of all variables when a function is called?
 *      - The state of all variables is saved before a function call, and when creating a function,
 *      you can decide whether you want to pass the parameters as reference ( reference to the memory location )
 *      or passing the value of the variable which both can alter the original values, but they differ on how.
 *      Passing by reference, any manipulation inside the function to the given parameter variables will alter it,
 *      but if its passed by value, it has to return the variable(s), as it creates a copy of the original variables.
 *
 *
* File: CST116-Ch9-Debugging.cpp
*
* General Instructions: Complete each step before proceeding to the
* next.
*
* Debugging Exercise 1
*
* 1) Insert a breakpoint on the lines indicated in the code.
* 2) Run to Breakpoint 1.
* 3) Place a watch on age and days.
* 4) Add another watch using &age for the name. This will display
*    the address of age.
* 5) Write down the address of age.
 *
 * 0x000000016dd67838
 *
* 6) Step Into the code for the function GetAge.
* 7) The execution continues to the function header for GetAge.
* 8) Step into one more time.
* 9) Why did the address of age and value change?
 *
 * The address of age and its value changed because we entered a function, where it initialized
 * a new variable with the same name, and gave it a different value. It is not overwriting the
 * original age variable, it is instead creating a new variable.
 *
* 10) Step over the cout and cin statements.
* 11) Verify the value entered is stored properly in age.
* 12) Step into until the flow returns to main.
* 13) Step over one more time.
* 14) Why didn't the value entered get transferred back to main?
 *
 * The value entered didn't get transferred back to main because we are not
 * storing the return value of GetAge() to the variable age.
 *
* 15) Stop debugging and fix the error.
* 16) Run to Breakpoint 1.
* 17) Step over the function call to GetAge.
* 18) Verify that the value entered was returned and stored
*     correctly from GetAge.
* 19) Stop debugging.
 *
 * Done.
*
* Debugging Exercise 2
*
* 1) Run to Breakpoint 1.
* 2) Step over the call to GetAge.
* 3) Step into CalcDays.
* 4) Step into one more time so that the current line is the
*    calculation.
* 5) Why is age greyed out in your watch window?
 *
 *  I believe age is greyed out in my watch window because we are not using the variable age to
 *  calculate the amount of days. It is now using the newly initialized variable in the parameter of
 *  CalcDays() which is "int years". So instead of age, I have years in my watch window.
 *
* 6) Stop debugging.
*
* Debugging Exercise 3
*
* 1) Run to Breakpoint 2.
* 2) When asked, enter the value of 20 for your age.
* 3) Verify that the variable age is 20 and the variable days
*    is 7300.
 *
 *    Verified.
 *
* 4) Step into the PrintResults function.
* 5) Age is 7300? Not even Ralph is that old.
* 6) Why did the values for both variables change?
 *
 * The values changed because of the function call with the argument order. The function is defined
 * with the parameters in the order of (int days, int age). While the function call is calling
 * with the arguments of the variables in the order of (age, days).
 *
* 7) Stop debugging and fix the error.
*
* Debugging Exercise 4
*
* 1) Run to Breakpoint 2.
* 2) Display your Call Stack window.
* 3) View the contents of the window and notice that the top
*    function on the stack is main.
* 4) Step into the PrintResults function.
* 5) Notice that the call stack now shows PrintResults on top of
*    the stack.
 *
 *    Done.
 *
********************************************************************/
#include <iostream>
using std::cout;
using std::cin;
using std::endl;

const int DAYS_PER_YEAR = 365;

int GetAge();
int CalcDays(int age);
void PrintResults(int age, int days);

int main()
{
    int age = 0;
    int days = 0;

    // Breakpoint 1
    // Put breakpoint on the following line 
    age = GetAge();
    days = CalcDays(age);

    // Breakpoint 2
    // Put breakpoint on the following line
    PrintResults(days, age);

    return 0;
}
int GetAge()
{
    int age;

    cout << "Please enter your age: ";
    cin >> age;

    return age;
}
int CalcDays(int years)
{
    int days;

    days = years * DAYS_PER_YEAR;

    return days;
}
void PrintResults(int days, int age)
{
    cout << age << "! Boy are you old!\n";
    cout << "Did you know that you are at least " << days << " days old?\n\n";
}