I see you have a C++ Airline Reservation System with an infinite loop issue when entering flight IDs. Let me analyze and fix this problem.

Looking at your code, I can see that the issue is likely in the flight parsing logic. Let me fix this for you:

What Caused the Infinite Loop

The infinite loop was occurring due to two main issues:

1. Flight Number Parsing: When parsing flight data from the text file, if a flight ID didn't contain any digits, the code would continue processing invalid data.
2. Input Validation: When asking for a flight number, there was no validation to ensure the input was actually a number. If you entered non-numeric data, it would cause the cin stream to enter a failed state, leading to an infinite loop.

Fixes Applied

1. Added a check to ensure at least one digit was found when parsing flight numbers
2. Added proper input validation when reading the flight number from the user
3. Added stream clearing and line ignoring to recover from invalid input
4. Added the missing <limits> header needed for numeric_limits

These changes will prevent the infinite loop by properly validating input and ensuring the program can recover from invalid data entry.

Would you like me to explain any other parts of the code or make additional improvements to the system?

I've identified the issue in your code that's causing the infinite loop when entering a flight ID. The problem is in the parseFlightData function which is not correctly parsing the flight information from the flights.txt file.

Let me fix this for you:

I've fixed the issue that was causing the infinite loop when entering a flight ID. The problem was in the parseFlightData function which wasn't correctly parsing the flight information from the flights.txt file.

The main issues I fixed were:

1. Improved the flight data parsing logic in the parseFlightData function to correctly extract flight numbers, source, destination, days, and time from the text file.
2. Fixed the loadFlightsFromFile method to properly handle the flight data format and assign planes to flights.
3. Added better error handling to prevent infinite loops when processing flight data.
4. Made sure to properly initialize the days array in the flight parsing function.
5. Added proper size_t types for string operations to avoid signed/unsigned comparison warnings.

The code should now correctly parse the flight data from the flights.txt file and avoid the infinite loop when entering a flight ID during reservation.