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1.4.8 Pitfalls and Subtleties of Macros

In this section we describe some special rules that apply to macros and macro expansion, and point out certain cases in which the rules have counterintuitive consequences that you must watch out for.

1.4.8.1 Improperly Nested Constructs		Macros can contain unmatched parentheses.
1.4.8.2 Unintended Grouping of Arithmetic		Why apparently superfluous parentheses may be necessary to avoid incorrect grouping.
1.4.8.3 Swallowing the Semicolon		Macros that look like functions but expand into compound statements.
1.4.8.4 Duplication of Side Effects		Unsafe macros that cause trouble when arguments contain side effects.
1.4.8.5 Self-Referential Macros		Macros whose definitions use the macros' own names.
1.4.8.6 Separate Expansion of Macro Arguments		Actual arguments are checked for macro calls before they are substituted.
1.4.8.7 Cascaded Use of Macros		Macros whose definitions use other macros.
1.4.9 Newlines in Macro Arguments		Sometimes line numbers get confused.