The C ``Clockwise/Spiral Rule''
The 'Clockwise/Spiral Rule' is a mnemonic technique developed by David Anderson in 1994 to help C programmers parse complex variable declarations. The method involves spiraling through tokens in a declaration to translate them into plain English.
Why it matters
It remains a classic educational tool for understanding the often-confusing syntax of the C programming language.
[This was posted to comp.lang.c by its author, David Anderson, on 1994-05-06.]
There is a technique known as the ``Clockwise/Spiral Rule'' which enables any C programmer to parse in their head any C declaration!
Starting with the unknown element, move in a spiral/clockwise direction; when ecountering the following elements replace them with the corresponding english statements:
=> Array X size of... or Array undefined size of...
=> function passing type1 and type2 returning...
Keep doing this in a spiral/clockwise direction until all tokens have been covered.
Always resolve anything in parenthesis first!
We move in a spiral clockwise direction starting with `str' and the first character we see is a `[' so, that means we have an array, so...
Continue in a spiral clockwise direction, and the next thing we encounter is the `*' so, that means we have pointers, so...
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