C++ Program to take a value from the user as input the month number and print number of days in that month. Using user define functions.

#include <iostream>
using namespace std;

// Function to get the number of days in a month using pass-by-value
void getDaysInMonthByValue(int month) {
    int days;
    switch (month) {
        case 1: case 3: case 5: case 7: case 8: case 10: case 12:
            days = 31;
            break;
        case 4: case 6: case 9: case 11:
            days = 30;
            break;
        case 2:
            days = 28; // Assuming non-leap year for simplicity
            break;
        default:
            cout << "Invalid month number. Please enter a number between 1 and 12." << endl;
            return;
    }
    cout << "Using pass-by-value: Month " << month << " has " << days << " days." << endl;
}

// Function to get the number of days in a month using pass-by-reference
void getDaysInMonthByReference(int month, int &days) {
    switch (month) {
        case 1: case 3: case 5: case 7: case 8: case 10: case 12:
            days = 31;
            break;
        case 4: case 6: case 9: case 11:
            days = 30;
            break;
        case 2:
            days = 28; // Assuming non-leap year for simplicity
            break;
        default:
            days = -1; // Invalid month
            break;
    }
}

int main() {
    int month, daysByRef;

    // Input the month number
    cout << "Enter the month number (1-12): ";
    cin >> month;

    // Get the number of days using pass-by-value
    getDaysInMonthByValue(month);

    // Get the number of days using pass-by-reference
    getDaysInMonthByReference(month, daysByRef);
    if (daysByRef != -1) {
        cout << "Using pass-by-reference: Month " << month << " has " << daysByRef << " days." << endl;
    } else {
        cout << "Using pass-by-reference: Invalid month number. Please enter a number between 1 and 12." << endl;
    }

    return 0;
}

#include <iostream>

using namespace std;

// Function to get the number of days in a month using pass-by-value

void getDaysInMonthByValue(int month) {

int days;

switch (month) {

case 1: case 3: case 5: case 7: case 8: case 10: case 12:

days = 31;

break;

case 4: case 6: case 9: case 11:

days = 30;

break;

case 2:

days = 28; // Assuming non-leap year for simplicity

break;

default:

cout << "Invalid month number. Please enter a number between 1 and 12." << endl;

return;

}

cout << "Using pass-by-value: Month " << month << " has " << days << " days." << endl;

}

// Function to get the number of days in a month using pass-by-reference

void getDaysInMonthByReference(int month, int &days) {

switch (month) {

case 1: case 3: case 5: case 7: case 8: case 10: case 12:

days = 31;

break;

case 4: case 6: case 9: case 11:

days = 30;

break;

case 2:

days = 28; // Assuming non-leap year for simplicity

break;

default:

days = -1; // Invalid month

break;

}

int main() {

int month, daysByRef;

// Input the month number

cout << "Enter the month number (1-12): ";

cin >> month;

// Get the number of days using pass-by-value

getDaysInMonthByValue(month);

// Get the number of days using pass-by-reference

getDaysInMonthByReference(month, daysByRef);

if (daysByRef != -1) {

cout << "Using pass-by-reference: Month " << month << " has " << daysByRef << " days." << endl;

} else {

cout << "Using pass-by-reference: Invalid month number. Please enter a number between 1 and 12." << endl;

}

return 0;

}

Explanation:

Pass-by-Value (getDaysInMonthByValue):
- Function Definition: void getDaysInMonthByValue(int month)
- This function takes the month number month as a parameter by value.
- It uses a switch statement to determine the number of days in the month.
- It prints the result directly.
Pass-by-Reference (getDaysInMonthByReference):
- Function Definition: void getDaysInMonthByReference(int month, int &days)
- This function takes the month number month by value and a reference to an int variable days.
- It uses a switch statement to determine the number of days and updates the days reference variable accordingly.
- The result is updated through the reference variable, and the function does not print directly. Instead, it relies on the main function to handle the output.
Main Function (main):
- Prompts the user to input a month number (from 1 to 12).
- It uses both pass-by-value and pass-by-reference methods to get and display the number of days in the month.

Example Outputs:

Example 1: Input:

Month number: 2

Output:

Enter the month number (1-12): 2
Using pass-by-value: Month 2 has 28 days.
Using pass-by-reference: Month 2 has 28 days.

Enter the month number (1-12): 2

Using pass-by-value: Month 2 has 28 days.

Using pass-by-reference: Month 2 has 28 days.

Example 2: Input:

Month number: 4

Output:

Enter the month number (1-12): 4
Using pass-by-value: Month 4 has 30 days.
Using pass-by-reference: Month 4 has 30 days.

Enter the month number (1-12): 4

Using pass-by-value: Month 4 has 30 days.

Using pass-by-reference: Month 4 has 30 days.

Example 3: Input:

Month number: 13

Output:

Enter the month number (1-12): 13
Invalid month number. Please enter a number between 1 and 12.
Using pass-by-reference: Invalid month number. Please enter a number between 1 and 12.

Enter the month number (1-12): 13

Invalid month number. Please enter a number between 1 and 12.

Using pass-by-reference: Invalid month number. Please enter a number between 1 and 12.

Explanation:

Example Outputs:

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