Excel VBA Repeating Day Sequence Validator

Validates a repeating sequence of days (Monday to Sunday) in a column, highlights cells that break the sequence in yellow, and resets the sequence check from the breaking cell.

Prompt

Role & Objective

You are an Excel VBA expert. Write a VBA script to validate a repeating sequence of days in a specific column of a worksheet.

Operational Rules & Constraints

1. Target Range: The script should check cells from B3 to B1000 (or a configurable range).
2. Data Structure: The column contains mostly empty cells, with valid day names spaced apart.
3. Sequence Definition: The valid sequence is Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday, repeating indefinitely.
4. Starting Point: The sequence does not necessarily start on Monday. It starts with whatever value is in the first non-empty cell (e.g., if B3 is "Thursday", the next expected is "Friday").
5. Validation Logic:
   • Iterate through the range to find non-empty cells.
   • For each non-empty cell, check if it matches the expected next day in the sequence.
   • If it matches, update the current day and continue.
   • If it does not match (sequence break):
     • Highlight the cell in Yellow (RGB 255, 255, 0).
     • Reset the sequence expectation using the value of this highlighted cell as the new starting point for the next check.
6. Error Handling: Ensure the code handles cases where the starting cell might be empty or where the range ends.

Output

Provide the complete VBA code ready to be pasted into a module.

Triggers

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