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<html lang="en"><head><title>Using the GNU Compiler Collection (GCC)</title><meta http-equiv="Content-Type" content="text/html"><meta name="description" content="Using the GNU Compiler Collection (GCC)"><meta name="generator" content="makeinfo 4.6"><!--Copyright © 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. <p>Permission is granted to copy, distribute and/or modify this documentunder the terms of the GNU Free Documentation License, Version 1.2 orany later version published by the Free Software Foundation; with theInvariant Sections being "GNU General Public License" and "FundingFree Software", the Front-Cover texts being (a) (see below), and withthe Back-Cover Texts being (b) (see below). A copy of the license isincluded in the section entitled "GNU Free Documentation License". <p>(a) The FSF's Front-Cover Text is: <p>A GNU Manual <p>(b) The FSF's Back-Cover Text is: <p>You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development.--><meta http-equiv="Content-Style-Type" content="text/css"><style type="text/css"><!-- pre.display { font-family:inherit } pre.format { font-family:inherit } pre.smalldisplay { font-family:inherit; font-size:smaller } pre.smallformat { font-family:inherit; font-size:smaller } pre.smallexample { font-size:smaller } pre.smalllisp { font-size:smaller }--></style></head><body><div class="node"><p>Node: <a name="Alternate%20Keywords">Alternate Keywords</a>,Next: <a rel="next" accesskey="n" href="Incomplete-Enums.html#Incomplete%20Enums">Incomplete Enums</a>,Previous: <a rel="previous" accesskey="p" href="Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>,Up: <a rel="up" accesskey="u" href="C-Extensions.html#C%20Extensions">C Extensions</a><hr><br></div><h3 class="section">Alternate Keywords</h3><p><code>-ansi</code> and the various <code>-std</code> options disable certainkeywords. This causes trouble when you want to use GNU C extensions, ora general-purpose header file that should be usable by all programs,including ISO C programs. The keywords <code>asm</code>, <code>typeof</code> and<code>inline</code> are not available in programs compiled with<code>-ansi</code> or <code>-std</code> (although <code>inline</code> can be used in aprogram compiled with <code>-std=c99</code>). The ISO C99 keyword<code>restrict</code> is only available when <code>-std=gnu99</code> (which willeventually be the default) or <code>-std=c99</code> (or the equivalent<code>-std=iso9899:1999</code>) is used. <p>The way to solve these problems is to put <code>__</code> at the beginning andend of each problematical keyword. For example, use <code>__asm__</code>instead of <code>asm</code>, and <code>__inline__</code> instead of <code>inline</code>. <p>Other C compilers won't accept these alternative keywords; if you want tocompile with another compiler, you can define the alternate keywords asmacros to replace them with the customary keywords. It looks like this:<pre class="smallexample"> #ifndef __GNUC__ #define __asm__ asm #endif </pre> <p><code>-pedantic</code> and other options cause warnings for many GNU C extensions. You canprevent such warnings within one expression by writing<code>__extension__</code> before the expression. <code>__extension__</code> has noeffect aside from this. </body></html>⌨️ 快捷键说明
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