Program doy in Example \(4.3\) calculates the day of year associated with any given month, day, and year. As written, this program docs not check to sce if the data entered by the user is valid. It will accept nonsense values for months and days and do calculations with them to produce meaningless results. Modify the program so that it checks the input values for validity before using them. If the inputs are invalid, the program should tell the user what is wrong and quit. The year should be a number greater than zero, the month should be a number between 1 and 12 , and the day should be a number between 1 and a maximum that depends on the month. Use a switch construct to implement the bounds checking performed on the day.

To modify the program to check the validity of user inputs, follow these steps: Step 1: Check the year validity - Ensure the entered year is greater than zero. If not, display an error message and exit the program. Step 2: Check the month validity - Ensure the entered month is between 1 and 12. If not, display an error message and exit the program. Step 3: Check the day validity - Use a switch statement to set the maximum value for the day depending on the month (e.g., 31 for January, 28 or 29 for February depending on leap year, etc.). If the entered day is not within the valid range for that month, display an error message and exit the program. Step 4: Calculate the day of the year - If all input values are valid, use the given program logic to calculate the day of the year.