C++ Write a program that prompts the user to enter a person's date of birth in numeric form (Throw/Catch)

ONLINECAST

2 min read

·

06-10-2024

7

0

Share

Handling User Input Errors Gracefully: A C++ Date of Birth Program with Exception Handling

Many programming challenges involve user input, which can be unpredictable. Ensuring your code handles unexpected inputs gracefully is crucial for a robust and user-friendly program. This article explores a C++ program that prompts the user to enter their date of birth in numeric form and demonstrates how to handle potential errors using exception handling.

The Problem: Invalid User Input

Imagine a program that needs to collect a user's date of birth. What happens if the user enters an invalid date format, like "13/13/1999" or "02-29-2023" (an invalid leap year)? Without proper error handling, your program might crash or produce incorrect results.

C++ Implementation with Exception Handling

Let's see a C++ program that handles such errors effectively:

#include <iostream>
#include <string>
#include <limits>

using namespace std;

int main() {
  int day, month, year;

  cout << "Enter your date of birth (dd mm yyyy): ";

  try {
    // Input validation using cin.fail()
    if (!(cin >> day >> month >> year)) {
      throw invalid_argument("Invalid date format. Please enter numbers in dd mm yyyy format.");
    }

    // Additional validation for date range
    if (day < 1 || day > 31 || month < 1 || month > 12 || year < 1900 || year > 2023) {
      throw out_of_range("Date out of valid range.");
    }

    cout << "Your date of birth is: " << day << "/" << month << "/" << year << endl;
  } catch (const invalid_argument& e) {
    cerr << "Error: " << e.what() << endl;
    cin.clear(); // Clear the error state of cin
    cin.ignore(numeric_limits<streamsize>::max(), '\n'); // Discard remaining input
    cout << "Please try again." << endl;
  } catch (const out_of_range& e) {
    cerr << "Error: " << e.what() << endl;
    cout << "Please enter a valid date within the specified range." << endl;
  }

  return 0;
}

Understanding the Code

1. Input Validation: The program uses cin >> day >> month >> year to read the user's input. The cin.fail() function checks if the input operation was successful. If it fails (e.g., the user enters non-numeric characters), an invalid_argument exception is thrown.

2. Date Range Validation: Further validation is done to ensure the entered date falls within a reasonable range. The code checks if the day, month, and year are within expected limits. If the date is outside the acceptable range, an out_of_range exception is thrown.

3. Exception Handling: The try-catch block allows us to catch specific exceptions.

   • If an invalid_argument is caught, an error message is displayed, and the program clears the error state of cin and discards remaining input using cin.ignore().
   • If an out_of_range exception is caught, a specific error message is displayed, and the user is prompted to enter a valid date.

Key Benefits of Exception Handling

• Robustness: Exception handling prevents program crashes and ensures your program continues to run even in the face of invalid input.
• Clarity: By explicitly throwing and catching exceptions, you separate error handling logic from the main program flow, improving code readability and maintainability.
• Customization: You can define custom exception classes to represent specific errors in your application, making it easier to diagnose and handle different types of problems.

Conclusion

This article showcased how exception handling in C++ can significantly improve the reliability and user experience of your programs. By handling potential errors gracefully, you can ensure a smoother and more robust application. Remember to implement comprehensive validation and error handling to provide a positive user experience and ensure the accuracy of your code.