[Main]
Name=GetArgType
Type=Function
Subtype=Macro
Header Files=args.h
Definition=unsigned char GetArgType (CESI ap);
Real Definition=#define GetArgType(p) (*(CESI)(p))

[Description]
Returns the type of the current argument.

[Explanation]
GetArgType returns a one-byte value which determines the type of the current argument
(pointed to by <I>ap</I>). There are many types of arguments: strings, integers
(positive or negative), fractions, floats, symbols, various algebraic expressions,
lists, matrices, etc. The enum <A HREF="$$LINK(estack.h/Tags)">Tags</A>
defines a lot of constants: the most commonly used in argument lists are
STR_TAG, POSINT_TAG, NEGINT_TAG, FLOAT_TAG, POSFRAC_TAG, ENDFRAC_TAG,
COMPLEX_TAG, LIST_TAG and END_TAG. They represent respectively a string, a positive integer, a negative
integer, a floating point value, a positive fraction, a negative fraction, a complex number,
a beginning of the list structure and an end-of-list marker (which also has meaning "no more arguments").
Any values except these need to be regarded as "an expression": you need to handle them
"by hand" (of course, if you know how).
See <A HREF="$$LINK(InitArgPtr)">InitArgPtr</A> for an example of usage.<BR><BR>
<B>Note:</B> You can use <A HREF="$$LINK(SkipArg)">SkipArg</A> to bypass the argument which you don't know
how to handle (or, which you don't want to handle for any reason).
