Start Visual Studio 2012 and create a new CLR Console Application project. Name the application CalendarAssistant.

At the top of the source code file, immediately below the using namespace System; line, add the following function prototypes (you will implement all these functions during this chapter):

int GetYear();
int GetMonth();
int GetDay(int year, int month);
void DisplayDate(int year, int month, int day);

At the end of the file, after the end of the main function, implement the GetYear function as follows:

int GetYear()
{
    Console::Write("Year? ");
    String ^input = Console::ReadLine();
    int year = Convert::ToInt32(input);
    return year;
}

Implement the GetMonth function as follows:

int GetMonth()
{
    Console::Write("Month? ");
    String ^input = Console::ReadLine();
    int month = Convert::ToInt32(input);
    return month;
}

This is a simplified implementation; later in this chapter, you will enhance the function to ensure that the user enters a valid month.

Implement the GetDay function as follows:

int GetDay(int year, int month)
{
    Console::Write("Day? ");
    String ^input = Console::ReadLine();
    int day = Convert::ToInt32(input);
    return day;
}

Later, you will enhance this function to ensure that the user enters a valid day for the given year and month.

Implement the DisplayDate function as shown in the following code to display the date as three numbers:

void DisplayDate(int year, int month, int day)
{
    Console::WriteLine("
This is the date you entered:");
    Console::Write(year);
    Console::Write("-");
    Console::Write(month);
    Console::Write("-");
    Console::Write(day);
    Console::WriteLine();
}

Later in this chapter you will enhance this function to display the date in a more user-friendly format.

Add the following code inside the main method, immediately before the return 0; Line:

Console::WriteLine("Welcome to your calendar assistant");
Console::WriteLine("
Please enter a date");
int year = GetYear();
int month = GetMonth();
int day = GetDay(year, month);
// Simplified test for now - assume there are 31 days in
// every month :-)
if (month >= 1 && month <= 12 && day >= 1 && day <= 31
)
{
    DisplayDate(year, month, day);
}
Console::WriteLine("
The end
");

This code asks the user to enter a year, month, and day. If the date passes a simplified validation test, the date is displayed on the console. If the date is invalid, it is not displayed at all.

Build the application and fix any compiler errors that you might have.

Run the application. Type in valid numbers for the year, month, and day (for example, 2012, 7, and 22).

The application displays the messages shown in the following screen shot:

Observe that the application displays the date because it is valid. The message “The End” also appears at the end of the program.

Run the application again, but this time, type an invalid date (for example, 2012, 2, and 33). The application displays the messages shown in the following screen shot:

Notice that because the date you typed was invalid, the application doesn’t display it. Instead, it just displays “The End.” You can make the application more user-friendly by displaying an error message if the date is invalid. To do so, you need to use a two-way test.

Continue working with the project from the previous exercise.

Modify the main function, replacing the simple if with an if-else statement to test for valid or invalid dates.

if (month >= 1 && month <= 12 && day >= 1 && day <= 31
)
{
    DisplayDate(year, month, day);
}
else
{
    Console::WriteLine("Invalid date");
}
Console::WriteLine("
The end
");

Build and run the application. Type an invalid date such as 2001, 0, and 31.

The application now displays an error message, as demonstrated in the following screen shot:

Continue working with the project from the previous exercise.

Replace the GetDay function with the following code so that it uses an if-else-if statement to determine the maximum allowable number of days.

int GetDay(int year, int month)
{
    int maxDay;
    if (month == 4 || month == 6 || month == 9 || month == 11)
    {
        maxDay = 30;
    }
    else if (month == 2)
    {
        maxDay = 28;
    }
    else
    {
        maxDay = 31;
    }
    Console::Write("Day [1 to ");
    Console::Write(maxDay);
    Console::Write("]? ");

    String ^input = Console::ReadLine();
    int day = Convert::ToInt32(input);
    return day;
}

Build and run the application. Type the year 2012 and the month 1.

The application prompts you to enter a day between 1 and 31, as illustrated in the following screen shot:

Type a valid day and close the console window when the date is displayed.

Run the application again. Type the year 2012 and the month 2.

The application prompts you to enter a day between 1 and 28, as shown here:

Type a valid day and close the console window when the date is displayed. (Don’t worry about the date validation in main: You will remove it later and replace it with more comprehensive validation in the GetMonth and GetDay functions.)

Continue working with the project from the previous exercise.

Modify the GetDay function, replacing the if…else if…else statements to match the block of code just described to test for leap years.

Build and run the application. Type the year 1996 and the month 2. The application prompts you to enter a day between 1 and 29. Type a valid day and then when the date is displayed, close the console window.

Run the application again. Type the year 1997 and the month 2. Verify that the application prompts you to enter a day between 1 and 28.

Run the application several more times using the test data from the previous table.

Continue working with the project from the previous exercise.

Modify the DisplayDate function. Rather than display the month as an integer, replace the Console::Write(month) statement with a switch statement that displays the month as a string.

switch (month)
{
    case 1:  Console::Write("January");   break;
    case 2:  Console::Write("February");  break;
    case 3:  Console::Write("March");     break;
    case 4:  Console::Write("April");     break;
    case 5:  Console::Write("May");       break;
    case 6:  Console::Write("June");      break;
    case 7:  Console::Write("July");      break;
    case 8:  Console::Write("August");    break;
    case 9:  Console::Write("September"); break;
    case 10: Console::Write("October");   break;
    case 11: Console::Write("November");  break;
    case 12: Console::Write("December");  break;
    default: Console::Write("Unknown");   break;
}

Build the application.

Run the application several times, typing a different month each time. Verify that the application displays the correct month name each time.

Continue working with the project from the previous exercise.

Modify the DisplayDate function. After displaying the year, month, and day, add the following code after the line Console::Write(day) to display the season:

switch (month)
{
    case 12:
    case 1:
    case 2:  Console::WriteLine(" [Winter]"); break;

    case 3:
    case 4:
    case 5:  Console::WriteLine(" [Spring]"); break;

    case 6:
    case 7:
    case 8:  Console::WriteLine(" [Summer]"); break;

    case 9:
    case 10:
    case 11: Console::WriteLine(" [Fall]"); break;
}

Build the application.

Run the application several times, typing a different month each time. Verify that the application displays the correct season name each time.

Continue working with the project from the previous exercise.

Modify the code in the main function by replacing the entire body of the function with the following code:

Console::WriteLine("Welcome to your calendar assistant");

int count = 1;    // Declare and initialize the loop counter
while (count <= 5)   // Test the loop counter
{
    Console::Write("
Please enter a date ");
    Console::WriteLine(count);

    int year = GetYear();
    int month = GetMonth();
    int day = GetDay(year, month);
    DisplayDate(year, month, day);

    count++;   // Increment the loop counter
}

Build and run the application. The application prompts you to enter the first date. After you have typed this date, the application prompts you to enter the second date. This process continues until you have typed five dates, at which point the application closes, as depicted in the following screen shot:

Continue working with the project from the previous exercise.

Modify the code in the main function to use a for loop rather than a while loop, as shown here:

Console::WriteLine("Welcome to your calendar assistant");

for (int count = 1; count <= 5; count++)
{
    Console::Write("
Please enter date ");
    Console::WriteLine(count);

    int year = GetYear();
    int month = GetMonth();
    int day = GetDay(year, month);
    DisplayDate(year, month, day);
}

Notice that there is no count++ statement after displaying the date. This is because the for statement takes care of incrementing the loop counter.

Build and run the application. The application asks you to enter five dates, as before.

Continue working with the project from the previous exercise.

Modify the GetMonth function as follows, which forces the user to type a valid month:

int GetMonth()
{
    int month = 0;
    do
    {
        Console::Write("Month [1 to 12]? ");
        String ^input = Console::ReadLine();
        month = Convert::ToInt32(input);
    }
    while (month < 1 || month > 12);
    return month;
}

Modify the GetDay function as follows, which forces the user to type a valid day:

int GetDay(int year, int month)
{
    int day = 0;
    int maxDay;

    // Calculate maxDay, as before (code not shown here) ... ... ...

    do
    {
        Console::Write("Day [1 to ");
        Console::Write(maxDay);
        Console::Write("]? ");
        String ^input = Console::ReadLine();
        day = Convert::ToInt32(input);
    }
    while (day < 1 || day > maxDay);
    return day;
}

Build and run the application.

Try to type an invalid month. The application keeps asking you to enter another month until you type a value between 1 and 12, inclusive.

Try to type an invalid day. The application keeps asking you to enter another day until you type a valid number (which depends on your chosen year and month).

Continue working with the project from the previous exercise.

Modify the main function as follows, which gives the user the option to break or continue if desired:

Console::WriteLine("Welcome to your calendar assistant");
for (int count = 1; count <= 5; count++)
{
    Console::Write("
Please enter date ");
    Console::WriteLine(count);
    int year = GetYear();
    int month = GetMonth();
    int day = GetDay(year, month);

    Console::Write("Press B (break), C (continue), or ");
    Console::Write("anything else to display date ");
    String ^input = Console::ReadLine();
    if (input->Equals("B"))
    {
        break;
    }
    else if (input->Equals("C"))
    {
        continue;
    }
    DisplayDate(year, month, day);
}

Build and run the application.

After you type the first date, you are asked whether you want to break or continue. Press X (or any other key except B or C) and then press Enter to display the date as normal.

Type the second date, and then press C followed by Enter, which causes the continue statement to be executed.

The continue statement abandons the current iteration without displaying your date. Instead, you are asked to type the third date.

Type the third date and then press B, which causes the break statement to be executed. The break statement terminates the entire loop.