C++ Exercises: Number of days of a month from a given year and month

Last update on April 12 2025 12:57:00 (UTC/GMT +8 hours)

5. Compute the Number of Days in a Month for a Given Year and Month

Write a C++ program to compute the number of days in a month for a given year and month.

Sample Solution-1:

C++ Code:

#include <iostream> // Including the input/output stream library

using namespace std; // Using the standard namespace

// Function to check if a year is a leap year or not
bool is_leap_year(int y) {
  return y % 400 == 0 || (y % 4 == 0 && y % 100 != 0); // Returns true if the year is divisible by 400 or divisible by 4 but not by 100
}

// Function to get the number of days in a month for a given year
int no_of_days(int month, int year) {
  switch (month) { // Switch statement to check the month
  case 1:
  case 3:
  case 5:
  case 7:
  case 8:
  case 10:
  case 12:
    return 31; // Months with 31 days
    break;

  case 4:
  case 6:
  case 9:
  case 11:
    return 30; // Months with 30 days
    break;

  case 2:
    if (is_leap_year(year) == 1)
      return 29; // February in a leap year
    else
      return 28; // February in a non-leap year
    break;

  default:
    break;
  }

  return 0; // Return 0 if month input is invalid
}

// Main function
int main() {
  int year = 0; // Declaring an integer variable to store the year
  int month = 0; // Declaring an integer variable to store the month
  int days; // Declaring an integer variable to store the number of days

  cout << "Input Year: "; // Output message for user input of year
  cin >> year; // Inputting the year value
  cout << "Input Month: "; // Output message for user input of month
  cin >> month; // Inputting the month value

  if (year > 0 && (month > 0 && month < 13)) { // Checking if the year and month inputs are valid
    // Displaying the number of days in the given year and month
    cout << "Number of days of the year " << year << " and month " << month << " is: " << no_of_days(month, year) << endl;
  } else {
    cout << "Wrong year/month!"; // Displaying an error message for invalid year/month input
  }

  return 0; // Return 0 to indicate successful execution
}

Sample Output:

Input Year: 2019
Input Month: 04
Number of days of the year 2019 and month 4 is: 30

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to determine the number of days in any given month, accounting for leap years in February.
Write a C++ program that reads a year and a month and uses a switch-case structure to output the correct number of days.
Write a C++ program to calculate the number of days in a month by storing month-day mappings in an array and adjusting for leap years.
Write a C++ program that validates user input for month and year, then outputs the number of days in that month, handling invalid inputs appropriately.

Sample Solution-2:

C++ Code:

#include <iostream> // Including the input/output stream library

using namespace std; // Using the standard namespace

// Function to get the number of days in a month for a given year
int no_of_days(int month, int year) {
  if (month == 4 || month == 6 || month == 9 || month == 11) // Months with 30 days
  {
    return 30;
  } 
  else if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) // Months with 31 days
  {
    return 31;
  } 
  else if (month == 2 && ((year % 4 == 0 && year % 100 != 0) || (year % 100 == 0 && year % 400 == 0))) // February in a leap year or a non-leap year
  {
    return 29; // February has 29 days in a leap year
  } 
  else // Default case for February in a non-leap year
  {
    return 28; // February has 28 days in a non-leap year
  }
}

// Main function
int main() {
  int year = 0; // Declaring an integer variable to store the year
  int month = 0; // Declaring an integer variable to store the month

  cout << "Input Year: "; // Output message for user input of year
  cin >> year; // Inputting the year value
  cout << "Input Month: "; // Output message for user input of month
  cin >> month; // Inputting the month value

  if (year > 0 && (month > 0 && month < 13)) { // Checking if the year and month inputs are valid
    // Displaying the number of days in the given year and month
    cout << "Number of days of the year " << year << " and month " << month << " is: " << no_of_days(month, year) << endl;
  } else {
    cout << "Wrong year/month!"; // Displaying an error message for invalid year/month input
  }

  return 0; // Return 0 to indicate successful execution
}

Sample Output:

Input Year: 2019
Input Month: 04
Number of days of the year 2019 and month 4 is: 30

Flowchart:

C++ Code Editor:

Contribute your code and comments through Disqus.

Previous: Check whether a given year is a leap year not.
Next: Count the number of days between two given dates.