File indexing completed on 2024-11-24 04:34:43
0001 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 0002 <html> 0003 <!-- This document is an unofficial reference manual for LaTeX, a 0004 document preparation system, version of November 2018. 0005 0006 This manual was originally translated from LATEX.HLP v1.0a in the 0007 VMS Help Library. The pre-translation version was written by 0008 George D. Greenwade of Sam Houston State University. The 0009 LaTeX 2.09 version was written by Stephen Gilmore. The 0010 LaTeX2e version was adapted from this by Torsten Martinsen. Karl 0011 Berry made further updates and additions, and gratefully acknowledges 0012 using Hypertext Help with LaTeX, by Sheldon Green, and 0013 LaTeX Command Summary (for LaTeX 2.09) by 0014 L. Botway and C. Biemesderfer (published by the TeX Users 0015 Group as TeXniques number 10), as reference material. We also 0016 gratefully acknowledge additional material appearing in 0017 latex2e-reference by Martin Herbert Dietze. (From these references no 0018 text was directly copied.) 0019 0020 Copyright 2007, 2008, 2009, 2010, 2011, 2012, 2013, 0021 2014, 2015, 2016, 2017, 2018 Karl Berry. 0022 0023 Copyright 1988, 1994, 2007 Stephen Gilmore. 0024 0025 Copyright 1994, 1995, 1996 Torsten Martinsen. 0026 0027 Permission is granted to make and distribute verbatim copies of 0028 this manual provided the copyright notice and this permission notice 0029 are preserved on all copies. 0030 0031 0032 Permission is granted to copy and distribute modified versions of this 0033 manual under the conditions for verbatim copying, provided that the entire 0034 resulting derived work is distributed under the terms of a permission 0035 notice identical to this one. 0036 0037 Permission is granted to copy and distribute translations of this manual 0038 into another language, under the above conditions for modified versions. --> 0039 <!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ --> 0040 <head> 0041 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 0042 <title>\@ifstar (LaTeX2e unofficial reference manual (November 2018))</title> 0043 0044 <meta name="description" content="\@ifstar (LaTeX2e unofficial reference manual (November 2018))"> 0045 <meta name="keywords" content="\@ifstar (LaTeX2e unofficial reference manual (November 2018))"> 0046 <meta name="resource-type" content="document"> 0047 <meta name="distribution" content="global"> 0048 <meta name="Generator" content="makeinfo"> 0049 <link href="index.html#Top" rel="start" title="Top"> 0050 <link href="IndexDocument.html#Index" rel="index" title="Index"> 0051 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> 0052 <link href="Definitions.html#Definitions" rel="up" title="Definitions"> 0053 <link href="_005cnewcounter.html#g_t_005cnewcounter" rel="next" title="\newcounter"> 0054 <link href="_005cmakeatletter-_0026-_005cmakeatother.html#g_t_005cmakeatletter-_0026-_005cmakeatother" rel="prev" title="\makeatletter & \makeatother"> 0055 <style type="text/css"> 0056 <!-- 0057 /* $Id: latex2e.css 690 2018-09-15 15:20:19Z jimhefferon $ 0058 Minor css for latexrefman. Public domain. 0059 Originally written by Jim Hefferon and Karl Berry, 2018. */ 0060 0061 /* So you can style for yourself */ 0062 @import url("/css/latexreflocal.css"); 0063 0064 0065 0066 a.summary-letter {text-decoration: none} 0067 blockquote.indentedblock {margin-right: 0em} 0068 blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} 0069 blockquote.smallquotation {font-size: smaller} 0070 div.display {margin-left: 3.2em} 0071 div.example {margin-left: 3.2em} 0072 div.lisp {margin-left: 3.2em} 0073 div.smalldisplay {margin-left: 3.2em} 0074 div.smallexample {margin-left: 3.2em} 0075 div.smalllisp {margin-left: 3.2em} 0076 kbd {font-style: oblique} 0077 pre.display {font-family: inherit} 0078 pre.format {font-family: inherit} 0079 pre.menu-comment {font-family: serif} 0080 pre.menu-preformatted {font-family: serif} 0081 pre.smalldisplay {font-family: inherit; font-size: smaller} 0082 pre.smallexample {font-size: smaller} 0083 pre.smallformat {font-family: inherit; font-size: smaller} 0084 pre.smalllisp {font-size: smaller} 0085 span.nolinebreak {white-space: nowrap} 0086 span.roman {font-family: initial; font-weight: normal} 0087 span.sansserif {font-family: sans-serif; font-weight: normal} 0088 ul.no-bullet {list-style: none} 0089 BODY { 0090 margin-top: 1em; 0091 margin-left: 1em; /* auto results in two-digit <ol> lost off left */ 0092 margin-right: 1em; 0093 margin-bottom: 1em; 0094 /* the idea is to use the whole window, unless it is ridiculously 0095 wide, probably with too-small fonts, too. */ 0096 max-width: 64em; 0097 } 0098 0099 /* Because we want @math{... @code ...} to be upright, not slanted, 0100 and Texinfo won't fix it. */ 0101 code {font-style:normal; font-family:monospace; } 0102 0103 /* We put a link to our own home page at the bottom. */ 0104 div.referenceinfo {font-size:small;} 0105 0106 --> 0107 </style> 0108 0109 0110 </head> 0111 0112 <body lang="en"> 0113 <a name="g_t_005c_0040ifstar"></a> 0114 <div class="header"> 0115 <p> 0116 Next: <a href="_005cnewcounter.html#g_t_005cnewcounter" accesskey="n" rel="next">\newcounter</a>, Previous: <a href="_005cmakeatletter-_0026-_005cmakeatother.html#g_t_005cmakeatletter-_0026-_005cmakeatother" accesskey="p" rel="prev">\makeatletter & \makeatother</a>, Up: <a href="Definitions.html#Definitions" accesskey="u" rel="up">Definitions</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="IndexDocument.html#Index" title="Index" rel="index">Index</a>]</p> 0117 </div> 0118 <hr> 0119 <a name="g_t_005c_0040ifstar-1"></a> 0120 <h3 class="section">12.4 <code>\@ifstar</code></h3> 0121 0122 <a name="index-_005c_0040ifstar"></a> 0123 <a name="index-commands_002c-star_002dvariants"></a> 0124 <a name="index-star_002dvariants_002c-commands"></a> 0125 0126 <p>Synopsis: 0127 </p> 0128 <div class="example"> 0129 <pre class="example">\newcommand{\mycmd}{\@ifstar{\mycmd@star}{\mycmd@nostar}} 0130 \newcommand{\mycmd@nostar}[<var>nostar-num-args</var>]{<var>nostar-body</var>} 0131 \newcommand{\mycmd@star}[<var>star-num-args</var>]{<var>star-body</var>} 0132 </pre></div> 0133 0134 <p>Many standard LaTeX environments or commands have a variant with the 0135 same name but ending with a star character <code>*</code>, an asterisk. 0136 Examples are the <code>table</code> and <code>table*</code> environments and the 0137 <code>\section</code> and <code>\section*</code> commands. 0138 </p> 0139 <p>When defining environments, following this pattern is straightforward 0140 because <code>\newenvironment</code> and <code>\renewenvironment</code> allow the 0141 environment name to contain a star. For commands the situation is more 0142 complex. As in the synopsis above, there will be a user-called command, 0143 given above as <code>\mycmd</code>, which peeks ahead to see if it is followed 0144 by a star. For instance, LaTeX does not really have a 0145 <code>\section*</code> command; instead, the <code>\section</code> command peeks 0146 ahead. This command does not accept arguments but instead expands to 0147 one of two commands that do accept arguments. In the synopsis these two 0148 are <code>\mycmd@nostar</code> and <code>\mycmd@star</code>. They could take the 0149 same number of arguments or a different number, or no arguments at all. 0150 As always, in a LaTeX document a command using at-sign <code>@</code> 0151 must be enclosed inside a <code>\makeatletter ... \makeatother</code> block 0152 (see <a href="_005cmakeatletter-_0026-_005cmakeatother.html#g_t_005cmakeatletter-_0026-_005cmakeatother">\makeatletter & \makeatother</a>). 0153 </p> 0154 <p>This example of <code>\@ifstar</code> defines the command <code>\ciel</code> and a 0155 variant <code>\ciel*</code>. Both have one required argument. A call to 0156 <code>\ciel{night}</code> will return "starry night sky" while 0157 <code>\ciel*{blue}</code> will return "starry not blue sky". 0158 </p> 0159 <div class="example"> 0160 <pre class="example">\newcommand*{\ciel@unstarred}[1]{starry #1 sky} 0161 \newcommand*{\ciel@starred}[1]{starry not #1 sky} 0162 \newcommand*{\ciel}{\@ifstar{\ciel@starred}{\ciel@unstarred}} 0163 </pre></div> 0164 0165 <p>In the next example, the starred variant takes a different number of 0166 arguments than the unstarred one. With this definition, Agent 007’s 0167 <code>``My name is \agentsecret*{Bond}, 0168 \agentsecret{James}{Bond}.''</code> is equivalent to entering the commands 0169 <code>``My name is \textsc{Bond}, \textit{James} textsc{Bond}.''</code> 0170 </p> 0171 <div class="example"> 0172 <pre class="example">\newcommand*{\agentsecret@unstarred}[2]{\textit{#1} \textsc{#2}} 0173 \newcommand*{\agentsecret@starred}[1]{\textsc{#1}} 0174 \newcommand*{\agentsecret}{% 0175 \@ifstar{\agentsecret@starred}{\agentsecret@unstarred}} 0176 </pre></div> 0177 0178 <p>There are two sometimes more convenient ways to accomplish the work of 0179 <code>\@ifstar</code>. The <samp>suffix</samp> package allows the construct 0180 <code>\newcommand\mycommand{<var>unstarred version</var>}</code> followed by 0181 <code>\WithSuffix\newcommand\mycommand*{<var>starred version</var>}</code>. And 0182 LaTeX3 has the <samp>xparse</samp> package that allows this code. 0183 </p> 0184 <div class="example"> 0185 <pre class="example">\NewDocumentCommand\foo{s}{\IfBooleanTF#1 0186 {<var>starred version</var>}% 0187 {<var>unstarred version</var>}% 0188 } 0189 </pre></div> 0190 0191 0192 0193 0194 <hr/><div class='referenceinfo'> <a href='https://latexref.xyz/'> <i>Unofficial LaTeX2e reference manual</i></a></div> 0195 </body> 0196 </html>