Question

Write a function definition for a function called before that takes two arguments of the type DayofYear, which is defined in Display \(11.1 .\) The function returns a bool value and returns true if the first argument represents a date that comes before the date represented by the second argument; otherwise, the function returns false. For example, January 5 comes before February 2

Short answer

Question: Write a function named "before" that takes two arguments of the type DayofYear and returns a bool value. The function should return true if the first argument represents a date that comes before the second argument date, and false otherwise.

Step-by-step solution

Function definition

Begin by defining the function with the given name "before" and specifying that it takes two arguments of the type "DayofYear". In our example, we can call the arguments day1 and day2. ```cpp bool before(DayofYear day1, DayofYear day2) { // Function implementation } ```

Comparing the month values

In order to determine if one date comes before another, first, we need to compare the month values of each date. If the month of the first date (day1.month) is smaller than the month of the second date (day2.month), the function should return true (that day1 is before day2). If the first date's month is larger, return false. If their month values are equal, proceed to step 3. ```cpp bool before(DayofYear day1, DayofYear day2) { if (day1.month < day2.month) { return true; } else if (day1.month > day2.month) { return false; } // Continue to compare dates if month values are equal } ```

Comparing the day values

When the month values of both dates are equal, we need to compare the day values to determine their chronological order. If the first date's day value (day1.day) is smaller than the second date's day value (day2.day), return true (day1 is before day2). Otherwise, return false. ```cpp bool before(DayofYear day1, DayofYear day2) { if (day1.month < day2.month) { return true; } else if (day1.month > day2.month) { return false; } // Compare day values if month values are equal if (day1.day < day2.day) { return true; } else { return false; } } ``` Now the 'before' function is complete and will correctly compare two dates of the type DayofYear and determines if the first date comes before the second date.

Key concepts

Function Definition

When we talk about function definitions in C++, we're essentially creating a blueprint for a specific task that the function will perform. For the provided exercise, the task is to define a function named "before". This function is intended to compare two instances of a user-defined type, DayofYear. Here are some key points to keep in mind:

• The return type of the function is specified as bool, indicating that the function will return either true or false.
• The function takes two parameters, both of which are of the type DayofYear. This means that each argument passed to the function must be of this same type.

To create this function, you start with the following syntax:

bool before(DayofYear day1, DayofYear day2) {
  // Function implementation
}

Here, "day1" and "day2" are placeholders for actual data that will be compared. The function will operate based on these values to determine the chronological order of the dates they represent.

Parameter Comparison

Parameter comparison is at the heart of determining the relationship between two DayofYear objects, based on their date values. In this context, it involves comparing both month and day values to decide if one date precedes another.

• Month Comparison: The first step is to compare the 'month' part of each DayofYear object. If the month of day1 is less than that of day2, it immediately suggests that day1 comes first. Thus, the function will return true. Conversely, if day1's month is greater, the function returns false, since this means day1 comes after day2.

If the months are identical, the function must proceed to further comparison:

• Day Comparison: Here, if day1.day is less than day2.day, day1 is still regarded as the earlier date.

This two-step comparison process ensures that the function determines which of the two dates comes first accurately.

Boolean Return Values

Boolean return values are fundamental to the behavior of the "before" function. A bool as a return type signifies that the function's output is a judgement: true or false.

• Use of true: The function returns true when the first DayofYear argument (day1) represents a date that comes before the second argument (day2). This is the desired outcome when the intent is to check the chronological precedence of day1 over day2.
• Use of false: If day1 does not come before day2, the function returns false. This indicates that either the dates are in the same position or day1 comes after day2.

By design, this function leverages boolean logic to make clear, binary decisions. This clarity aids in code readability and reduces the likelihood of misinterpretation when the function is used within larger programs. Thus, boolean return values provide a convenient way to express conditional logic outcomes.