Downloads - Calendar Maker

### Program Description

The **Calendar** program is a monthly calendar generator tailored exclusively for the Casio fx-CP400 and fx-CG500 graphing calculators. Written in Casio Basic, this utility allows users to input any specific month and year within the current era to dynamically generate a clean, text-based calendar matrix on the screen.

At its operational core, the program utilizes a structured mathematical approach to date calculation. Upon receiving user input, it normalizes the month and year values to prepare them for Zeller's Congruence—a widely recognized algorithm used to determine the exact day of the week for any calendar date. The algorithmic calculation is offloaded to a separate, optimized helper function named **day**. This function processes the century, year, and month parameters to calculate an integer representing the first day of the week.

Once this starting day is established, **Calendar** applies leap year logic for February , determines the exact day count for the selected month , and prints an aligned "Sun Mon Tue Wed Thu Fri Sat" grid layout. It eliminates manual scheduling guesswork, making it a highly efficient utility for tracking dates directly on your ClassPad device.

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### How to Use

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**Launch the Program:** Open the **Program** application on your Casio fx-CP400 or fx-CG500, locate `Calendar`, and execute it.


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**Provide Inputs:** * When prompted with *"Enter month (1-12):"*, type the number corresponding to your desired month and press `EXE`.
* When prompted with *"Enter year"*, enter the full 4-digit year (e.g., 2026) and press `EXE`.
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**View the Calendar:** The calculator screen will clear and output the month abbreviation, the year, and the formatted calendar block.
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**Loop or Exit:** At the conclusion of the script, an interactive prompt will ask *"Any more calendars?[1:Yes 2:No]"*. Input `1` to start over, or input `2` to cleanly terminate the program execution.



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### Precautions for Placing the `day` Function in a Folder

Because the main `Calendar` script references an external user-defined function (`day(1,M,C,Y)`), proper file and directory management is critical within the ClassPad operating system:

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**Same-Folder Dependency:** By default, Casio Basic searches for custom functions within the *currently active directory* (typically the `main` folder). For the program to run successfully, both `Calendar` and `day` must reside in the exact same folder, *OR THE day FUNCTION MUST BE PLACED IN THE LIBRARY FOLDER.*


* **The Path Resolution Issue:** If you isolate the `day` function inside a specific subfolder (e.g., a folder named `MATH`), the main program will crash with an "Undefined variable or function" error because it cannot resolve a naked `day()` call from a different directory.
* **Code Correction Requirement:** If you must organize your files by placing the `day` function into a separate folder, you must PLACE THE day FUNCTION IN THE LIBRARY FOLDER.

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Also, this programme is still under development. Hence, any comments, suggestions, or reports on Bugs are always welcome.

### Disclaimer

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> **Notice:** This program is provided "as-is" for personal organization and educational purposes on compatible Casio ClassPad series calculators. While it incorporates leap year variations, it is not intended to replace official administrative scheduling software. Ensure your calculator's local system variables are cleared appropriately if the script is forcibly interrupted.
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