1<html lang="en"> 2<head> 3<title>Macro Pitfalls - The C Preprocessor</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="The C Preprocessor"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="Macros.html#Macros" title="Macros"> 9<link rel="prev" href="Directives-Within-Macro-Arguments.html#Directives-Within-Macro-Arguments" title="Directives Within Macro Arguments"> 10<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 11<!-- 12Copyright (C) 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 131997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 142008, 2009, 2010, 2011 15Free Software Foundation, Inc. 16 17Permission is granted to copy, distribute and/or modify this document 18under the terms of the GNU Free Documentation License, Version 1.3 or 19any later version published by the Free Software Foundation. A copy of 20the license is included in the 21section entitled ``GNU Free Documentation License''. 22 23This manual contains no Invariant Sections. The Front-Cover Texts are 24(a) (see below), and the Back-Cover Texts are (b) (see below). 25 26(a) The FSF's Front-Cover Text is: 27 28 A GNU Manual 29 30(b) The FSF's Back-Cover Text is: 31 32 You have freedom to copy and modify this GNU Manual, like GNU 33 software. Copies published by the Free Software Foundation raise 34 funds for GNU development. 35--> 36<meta http-equiv="Content-Style-Type" content="text/css"> 37<style type="text/css"><!-- 38 pre.display { font-family:inherit } 39 pre.format { font-family:inherit } 40 pre.smalldisplay { font-family:inherit; font-size:smaller } 41 pre.smallformat { font-family:inherit; font-size:smaller } 42 pre.smallexample { font-size:smaller } 43 pre.smalllisp { font-size:smaller } 44 span.sc { font-variant:small-caps } 45 span.roman { font-family:serif; font-weight:normal; } 46 span.sansserif { font-family:sans-serif; font-weight:normal; } 47--></style> 48<link rel="stylesheet" type="text/css" href="../cs.css"> 49</head> 50<body> 51<div class="node"> 52<a name="Macro-Pitfalls"></a> 53<p> 54Previous: <a rel="previous" accesskey="p" href="Directives-Within-Macro-Arguments.html#Directives-Within-Macro-Arguments">Directives Within Macro Arguments</a>, 55Up: <a rel="up" accesskey="u" href="Macros.html#Macros">Macros</a> 56<hr> 57</div> 58 59<h3 class="section">3.10 Macro Pitfalls</h3> 60 61<p><a name="index-problems-with-macros-72"></a><a name="index-pitfalls-of-macros-73"></a> 62In this section we describe some special rules that apply to macros and 63macro expansion, and point out certain cases in which the rules have 64counter-intuitive consequences that you must watch out for. 65 66<ul class="menu"> 67<li><a accesskey="1" href="Misnesting.html#Misnesting">Misnesting</a> 68<li><a accesskey="2" href="Operator-Precedence-Problems.html#Operator-Precedence-Problems">Operator Precedence Problems</a> 69<li><a accesskey="3" href="Swallowing-the-Semicolon.html#Swallowing-the-Semicolon">Swallowing the Semicolon</a> 70<li><a accesskey="4" href="Duplication-of-Side-Effects.html#Duplication-of-Side-Effects">Duplication of Side Effects</a> 71<li><a accesskey="5" href="Self_002dReferential-Macros.html#Self_002dReferential-Macros">Self-Referential Macros</a> 72<li><a accesskey="6" href="Argument-Prescan.html#Argument-Prescan">Argument Prescan</a> 73<li><a accesskey="7" href="Newlines-in-Arguments.html#Newlines-in-Arguments">Newlines in Arguments</a> 74</ul> 75 76 </body></html> 77 78