| <html lang="en"> |
| <head> |
| <title>Elif - The C Preprocessor</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="The C Preprocessor"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="Conditional-Syntax.html#Conditional-Syntax" title="Conditional Syntax"> |
| <link rel="prev" href="Else.html#Else" title="Else"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| Copyright (C) 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996, |
| 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, |
| 2008, 2009, 2010 |
| Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.2 or |
| any later version published by the Free Software Foundation. A copy of |
| the license is included in the |
| section entitled ``GNU Free Documentation License''. |
| |
| This manual contains no Invariant Sections. The Front-Cover Texts are |
| (a) (see below), and the Back-Cover Texts are (b) (see below). |
| |
| (a) The FSF's Front-Cover Text is: |
| |
| A GNU Manual |
| |
| (b) The FSF's Back-Cover Text is: |
| |
| 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 } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="Elif"></a> |
| <p> |
| Previous: <a rel="previous" accesskey="p" href="Else.html#Else">Else</a>, |
| Up: <a rel="up" accesskey="u" href="Conditional-Syntax.html#Conditional-Syntax">Conditional Syntax</a> |
| <hr> |
| </div> |
| |
| <h4 class="subsection">4.2.5 Elif</h4> |
| |
| <p><a name="index-g_t_0023elif-91"></a>One common case of nested conditionals is used to check for more than two |
| possible alternatives. For example, you might have |
| |
| <pre class="smallexample"> #if X == 1 |
| ... |
| #else /* X != 1 */ |
| #if X == 2 |
| ... |
| #else /* X != 2 */ |
| ... |
| #endif /* X != 2 */ |
| #endif /* X != 1 */ |
| </pre> |
| <p>Another conditional directive, ‘<samp><span class="samp">#elif</span></samp>’, allows this to be |
| abbreviated as follows: |
| |
| <pre class="smallexample"> #if X == 1 |
| ... |
| #elif X == 2 |
| ... |
| #else /* X != 2 and X != 1*/ |
| ... |
| #endif /* X != 2 and X != 1*/ |
| </pre> |
| <p>‘<samp><span class="samp">#elif</span></samp>’ stands for “else if”. Like ‘<samp><span class="samp">#else</span></samp>’, it goes in the |
| middle of a conditional group and subdivides it; it does not require a |
| matching ‘<samp><span class="samp">#endif</span></samp>’ of its own. Like ‘<samp><span class="samp">#if</span></samp>’, the ‘<samp><span class="samp">#elif</span></samp>’ |
| directive includes an expression to be tested. The text following the |
| ‘<samp><span class="samp">#elif</span></samp>’ is processed only if the original ‘<samp><span class="samp">#if</span></samp>’-condition |
| failed and the ‘<samp><span class="samp">#elif</span></samp>’ condition succeeds. |
| |
| <p>More than one ‘<samp><span class="samp">#elif</span></samp>’ can go in the same conditional group. Then |
| the text after each ‘<samp><span class="samp">#elif</span></samp>’ is processed only if the ‘<samp><span class="samp">#elif</span></samp>’ |
| condition succeeds after the original ‘<samp><span class="samp">#if</span></samp>’ and all previous |
| ‘<samp><span class="samp">#elif</span></samp>’ directives within it have failed. |
| |
| <p>‘<samp><span class="samp">#else</span></samp>’ is allowed after any number of ‘<samp><span class="samp">#elif</span></samp>’ directives, but |
| ‘<samp><span class="samp">#elif</span></samp>’ may not follow ‘<samp><span class="samp">#else</span></samp>’. |
| |
| </body></html> |
| |
