{"id":106,"date":"2010-05-13T20:43:14","date_gmt":"2010-05-13T19:43:14","guid":{"rendered":"http:\/\/blog.ludovicfavre.ch\/?p=106"},"modified":"2011-04-11T22:19:10","modified_gmt":"2011-04-11T21:19:10","slug":"parser-la-ligne-de-commande-avec-getopt_long","status":"publish","type":"post","link":"https:\/\/www.ludovicfavre.ch\/blog\/2010\/05\/parser-la-ligne-de-commande-avec-getopt_long\/","title":{"rendered":"Parser la ligne de commande avec getopt_long()"},"content":{"rendered":"

Durant un projet C\/C++, j’ai eu besoin de parser efficacement les arguments du programme. Le nombre d’options \u00e9tant devenu important, j’ai d\u00e9cid\u00e9 d’utiliser getopt_long, disponible avec GNU C<\/a>. Une fois l’outil pris en main, j’ai eu un peu de mal \u00e0 trouver comment se d\u00e9roulait le parsing des arguments n’\u00e9tant pas des options (nom de fichier par exemple). C’est finalement en tombant sur de la documentation oracle\/sun<\/a> que j’ai trouv\u00e9 la solution.<\/p>\n

Voici tout d’abord les d\u00e9clarations de base de pour utiliser getopt_long:<\/p>\n

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<\/div><\/td>
#include <getopt.h> \/\/requis pour l'utilisation de getopt_long<\/span>
\nstruct<\/span> globalArgs_t {<\/span>
\nunsigned<\/span> int<\/span> help;<\/span> \/* -h option*\/<\/span>
\nunsigned<\/span> int<\/span> algorithm;<\/span> \/* -t option *\/<\/span>
\nbool<\/span> toStdout ;<\/span> \/*-stdout option*\/<\/span>
\nbool<\/span> fromStdin ;<\/span> \/*-stdin option*\/<\/span>
\nstring*<\/span> infile;<\/span>
\nint<\/span> verbosity;<\/span> \/* -v option *\/<\/span>
\n}<\/span> globalArgs;<\/span>
\n
\nstatic<\/span> const<\/span> char<\/span> *<\/span>optString =<\/span> "t:h?;"<\/span>;<\/span>\/\/"Il:o:vh?"; \/\/pour plus de d\u00e9tails, cf doc GNU<\/span>
\n
\nstatic<\/span> const<\/span> struct<\/span> option longOpts[<\/span>]<\/span> =<\/span> {<\/span>
\n{<\/span> "help"<\/span>, no_argument, NULL<\/span>, 'h'<\/span> }<\/span>,
\n{<\/span> "algorithm"<\/span>, required_argument, NULL<\/span>, 't'<\/span> }<\/span>,
\n{<\/span> "stdin"<\/span>, no_argument, NULL<\/span>, 0<\/span> }<\/span>,
\n{<\/span> "stdout"<\/span>, no_argument, NULL<\/span>, 0<\/span> }<\/span>,
\n{<\/span> "verbose"<\/span>, no_argument, NULL<\/span>, 'v'<\/span> }<\/span>,
\n{<\/span>NULL<\/span>, 0<\/span>, NULL<\/span>, 0<\/span>}<\/span>
\n}<\/span>;<\/span><\/div><\/td><\/tr><\/tbody><\/table><\/div>\n

La premi\u00e8re structure\u00a0globalArgs<\/em> permet de stocker les valeurs pour les options de nos programmes (et les utiliser plus tard).<\/p>\n

La cha\u00eene\u00a0optString<\/em> permet de d\u00e9finir la structure des arguments. Les deux points signifient par exemple d’un param\u00e8tre est attendu pour l’option\u00a0-t<\/em>. Pour plus de d\u00e9tails, je vous conseille la doc GNU<\/a>.<\/p>\n

Enfin, le tableau d’option longOpts[]<\/em> permet de d\u00e9finir les options longues (sp\u00e9cifi\u00e9es par –option) ainsi que les options courtes comme -h<\/em> ou -t<\/em>.<\/p>\n

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<\/div><\/td>
int<\/span> parseCmd(<\/span>int<\/span> argc, char<\/span>**<\/span> argv)<\/span>
\n
\n{<\/span>
\n
\nint<\/span> longIndex;<\/span>
\nint<\/span> opt =<\/span> getopt_long(<\/span> argc, argv, optString, longOpts, &<\/span>amp;<\/span>longIndex )<\/span>;<\/span>
\nglobalArgs.algorithm<\/span> =<\/span> 0<\/span>;<\/span>
\nwhile<\/span> (<\/span> opt !<\/span>=<\/span> -<\/span>1<\/span> )<\/span> {<\/span>
\nswitch<\/span> (<\/span> opt )<\/span> {<\/span>
\ncase<\/span> 't'<\/span>:<\/span>
\nif<\/span> (<\/span> strcmp<\/span>(<\/span> "alg1"<\/span>, optarg )<\/span> ==<\/span> 0<\/span> )<\/span> {<\/span>
\nglobalArgs.algorithm<\/span> =<\/span> ALG1;<\/span>
\n}<\/span>
\n\/\/...<\/span>
\nif<\/span>(<\/span>globalArgs.algorithm<\/span> ==<\/span> 0<\/span>)<\/span>{<\/span>
\nfprintf<\/span>(<\/span>stderr<\/span>,"Invalid algorithm option, defaulting to alg5\\n<\/span>"<\/span>)<\/span>;<\/span>
\nglobalArgs.algorithm<\/span> =<\/span> ALG5;<\/span>
\n}<\/span>
\nbreak<\/span>;<\/span>
\n
\ncase<\/span> 'v'<\/span>:<\/span>
\nglobalArgs.verbosity<\/span>++<\/span>;<\/span> \/\/-vv will set verbosity to 2 for example<\/span>
\nbreak<\/span>;<\/span>
\n
\ncase<\/span> 'h'<\/span>:<\/span>   \/* fall-through is intentional *\/<\/span>
\ncase<\/span> '?'<\/span>:<\/span>
\ndisplayHelp(<\/span>)<\/span>;<\/span>
\nbreak<\/span>;<\/span>
\ncase<\/span> 0<\/span>:<\/span>     \/* long option without a short arg *\/<\/span>
\nfprintf<\/span>(<\/span>stderr<\/span>,"case 0"<\/span>)<\/span>;<\/span>
\nfiltered =<\/span> false<\/span>;<\/span>
\nif<\/span> (<\/span> strcmp<\/span>(<\/span> "stdin"<\/span>, longOpts[<\/span>longIndex]<\/span>.name<\/span> )<\/span> ==<\/span> 0<\/span> )<\/span> {<\/span>
\nglobalArgs.fromStdin<\/span> =<\/span> true<\/span>;<\/span>
\nfiltered =<\/span> true<\/span>;<\/span>
\n}<\/span>
\n
\nif<\/span> (<\/span> strcmp<\/span>(<\/span> "stdout"<\/span>, longOpts[<\/span>longIndex]<\/span>.name<\/span> )<\/span> ==<\/span> 0<\/span> )<\/span> {<\/span>
\nglobalArgs.toStdout<\/span> =<\/span> true<\/span>;<\/span>
\nfiltered =<\/span> true<\/span>;<\/span>
\n}<\/span>
\nbreak<\/span>;<\/span>
\n
\ndefault<\/span>:<\/span>
\n\/* You won't actually get here. *\/<\/span>
\nfprintf<\/span>(<\/span>stderr<\/span>,"Error parsing arguments..."<\/span>)<\/span>;<\/span>
\nreturn<\/span> -<\/span>1<\/span>;<\/span>
\nbreak<\/span>;<\/span>
\n}<\/span>
\n
\nopt =<\/span> getopt_long(<\/span> argc, argv, optString, longOpts, &<\/span>amp;<\/span>longIndex )<\/span>;<\/span>
\n}<\/span>
\nfor<\/span> (<\/span> ;<\/span> optind &<\/span>lt;<\/span> argc;<\/span> optind++<\/span>)<\/span> {<\/span>
\nif<\/span> (<\/span>access(<\/span>argv[<\/span>optind]<\/span>, R_OK)<\/span>)<\/span> {<\/span>
\n\/\/ c'est ici que l'on pourra r\u00e9cup\u00e9rer, par exemple, un non de fichier en entr\u00e9e et tenter de l'ouvrir<\/span>
\nfprintf<\/span>(<\/span>stderr<\/span>,"Non-option argument: %s\\n<\/span>"<\/span>,argv[<\/span>optind]<\/span>)<\/span>;<\/span>
\n}<\/span>
\n}<\/span>
\nreturn<\/span> 0<\/span>;<\/span>
\n}<\/span><\/div><\/td><\/tr><\/tbody><\/table><\/div>\n

L’appel \u00e0 getopt_long()<\/em> ne permet pas de r\u00e9cup\u00e9rer un non de fichier (par exemple) autrement qu’avec -i fichier<\/em>. Pour utiliser les arguments n’\u00e9tant pas des options, il faut proc\u00e9der comme ci-dessus en utilisant optind.
\n<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Durant un projet C\/C++, j’ai eu besoin de parser efficacement les arguments du programme. Le nombre d’options \u00e9tant devenu important, j’ai d\u00e9cid\u00e9 d’utiliser getopt_long, disponible avec GNU C. Une fois l’outil pris en main, j’ai eu un peu de mal \u00e0 trouver comment se d\u00e9roulait le parsing des arguments n’\u00e9tant pas des options (nom de fichier par exemple)… Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"footnotes":""},"categories":[1],"tags":[19,18,65,8],"class_list":["post-106","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-cc","tag-gnu","tag-linux","tag-unix"],"_links":{"self":[{"href":"https:\/\/www.ludovicfavre.ch\/blog\/wp-json\/wp\/v2\/posts\/106","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ludovicfavre.ch\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ludovicfavre.ch\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ludovicfavre.ch\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ludovicfavre.ch\/blog\/wp-json\/wp\/v2\/comments?post=106"}],"version-history":[{"count":15,"href":"https:\/\/www.ludovicfavre.ch\/blog\/wp-json\/wp\/v2\/posts\/106\/revisions"}],"predecessor-version":[{"id":115,"href":"https:\/\/www.ludovicfavre.ch\/blog\/wp-json\/wp\/v2\/posts\/106\/revisions\/115"}],"wp:attachment":[{"href":"https:\/\/www.ludovicfavre.ch\/blog\/wp-json\/wp\/v2\/media?parent=106"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ludovicfavre.ch\/blog\/wp-json\/wp\/v2\/categories?post=106"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ludovicfavre.ch\/blog\/wp-json\/wp\/v2\/tags?post=106"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}