Clockwise/Spiral Rule

【Clockwise/Spiral Rule】

　　There is a technique known as the ``Clockwise/Spiral Rule''. （顺时针螺旋法则）.

　　There are three simple steps to follow:

Starting with the unknown element, move in a spiral/clockwise direction; when ecountering the following elements replace them with the corresponding english statements:

[X] or []

=> Array X size of... or Array undefined size of...

(type1, type2)

=> function passing type1 and type2 returning...

*

=> pointer(s) to...
Keep doing this in a spiral/clockwise direction until all tokens have been covered.
Always resolve anything in parenthesis first!

Question we ask ourselves: What is str?

``str is an...

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...
``str is an array 10 of...
Continue in a spiral clockwise direction, and the next thing we encounter is the `*' so, that means we have pointers, so...
``str is an array 10 of pointers to...
Continue in a spiral direction and we see the end of the line (the `;'), so keep going and we get to the type `char', so...
``str is an array 10 of pointers to char''
We have now ``visited'' every token; therefore we are done!

　　 Clockwise/Spiral Rule

　　Question we ask ourselves: What is fp?

``fp is a...

Moving in a spiral clockwise direction, the first thing we see is a `)'; therefore, fp is inside parenthesis, so we continue the spiral inside the parenthesis and the next character seen is the `*', so...
``fp is a pointer to...
We are now out of the parenthesis and continuing in a spiral clockwise direction, we see the `('; therefore, we have a function, so...
``fp is a pointer to a function passing an int and a pointer to float returning...
Continuing in a spiral fashion, we then see the `*' character, so...
``fp is a pointer to a function passing an int and a pointer to float returning a pointer to...
Continuing in a spiral fashion we see the `;', but we haven't visited all tokens, so we continue and finally get to the type `char', so...
``fp is a pointer to a function passing an int and a pointer to float returning a pointer to a char''

　　 Clockwise/Spiral Rule 　　

　　Question we ask ourselves: What is `signal'?

　　Notice that signal is inside parenthesis, so we must resolve this first!

Moving in a clockwise direction we see `(' so we have...
``signal is a function passing an int and a...
Hmmm, we can use this same rule on `fp', so... What is fp? fp is also inside parenthesis so continuing we see an `*', so...
fp is a pointer to...
Continue in a spiral clockwise direction and we get to `(', so...
``fp is a pointer to a function passing int returning...''
Now we continue out of the function parenthesis and we see void, so...
``fp is a pointer to a function passing int returning nothing (void)''
We have finished with fp so let's catch up with `signal', we now have...
``signal is a function passing an int and a pointer to a function passing an int returning nothing (void) returning...
We are still inside parenthesis so the next character seen is a `*', so...
``signal is a function passing an int and a pointer to a function passing an int returning nothing (void) returning a pointer to...
We have now resolved the items within parenthesis, so continuing clockwise, we then see another `(', so...
``signal is a function passing an int and a pointer to a function passing an int returning nothing (void) returning a pointer to a function passing an int returning...
Finally we continue and the only thing left is the word `void', so the final complete definition for signal is:
``signal is a function passing an int and a pointer to a function passing an int returning nothing (void) returning a pointer to a function passing an int returning nothing (void)''

The same rule is applied for const and volatile. For Example:

	const char *chptr;

How about this one:

	char * const chptr;

Finally:

	volatile char * const chptr;

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