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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="Min%20and%20Max">Min and Max</a>,Next: <a rel="next" accesskey="n" href="Volatiles.html#Volatiles">Volatiles</a>,Up: <a rel="up" accesskey="u" href="C---Extensions.html#C++%20Extensions">C++ Extensions</a><hr><br></div><h3 class="section">Minimum and Maximum Operators in C++</h3><p>It is very convenient to have operators which return the "minimum" or the"maximum" of two arguments. In GNU C++ (but not in GNU C), <dl><dt><code></code><var>a</var><code> <? </code><var>b</var><code></code> <dd>is the <dfn>minimum</dfn>, returning the smaller of the numeric values<var>a</var> and <var>b</var>; <br><dt><code></code><var>a</var><code> >? </code><var>b</var><code></code> <dd>is the <dfn>maximum</dfn>, returning the larger of the numeric values <var>a</var>and <var>b</var>. </dl> <p>These operations are not primitive in ordinary C++, since you canuse a macro to return the minimum of two things in C++, as in thefollowing example.<pre class="smallexample"> #define MIN(X,Y) ((X) < (Y) ? : (X) : (Y)) </pre><p>You might then use <code>int min = MIN (i, j);</code> to set <var>min</var> tothe minimum value of variables <var>i</var> and <var>j</var>. <p>However, side effects in <code>X</code> or <code>Y</code> may cause unintendedbehavior. For example, <code>MIN (i++, j++)</code> will fail, incrementingthe smaller counter twice. The GNU C <code>typeof</code> extension allows youto write safe macros that avoid this kind of problem (see <a href="Typeof.html#Typeof">Typeof</a>). However, writing <code>MIN</code> and <code>MAX</code> as macros also forces you touse function-call notation for a fundamental arithmetic operation. Using GNU C++ extensions, you can write <code>int min = i <? j;</code>instead. <p>Since <code><?</code> and <code>>?</code> are built into the compiler, they properlyhandle expressions with side-effects; <code>int min = i++ <? j++;</code>works correctly. </body></html>⌨️ 快捷键说明
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