1. Patterns to KNOW

2. Sentinel Logic Priming input
While input does NOT meet sentinel condition
Do processing of valid input
Input again

3. Input (data) validation
Very similar to sentinel logic
The difference is in the meaning – “loop while data is BAD”, where Sentinel Logic is “loop while data is GOOD”
Priming input
While input does NOT meet valid data criteria
Report invalid data to user
Input data again

4. Flags – ANY pattern Set flag to False
Code to provide data to check (loop or series of if statements)
If condition to flag is detected
Set flag to True
After all data is processed
If flag is True, at least one value with condition has been seen
Else no value with condition has been seen

5. Flags – ALL pattern Set flag to True
Code to process data (while or series of if statements)
If condition to check does NOT hold, set flag to False
(note that this if does NOT have an else!)
After all data is processed
If flag is True, the condition was True for all values seen
Else at least one item with the condition False has been seen

6. Accumulating
Initialize the accumulator variable to the “empty” state for its data type, that is 0 or 0.0 for numbers, ‘’ (empty string) for strings, [] for lists, etc.
Process all the data as needed in loops, etc.
Use an accumulating statement variable operator= expression,
such as x += 1, sentence += word, z -= num, datalist += item

7. Previous - Current Obtain the first piece of data, call it previous
For all the other items of data
get another item of data, call it current
process data as needed, using both pieces of data prev and curr
then move current to previous (previous = current)