{"id":20980,"date":"2022-11-11T15:13:25","date_gmt":"2022-11-11T09:43:25","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-why-does-regex-work-well-in-java-but-does-not-work-in-c\/"},"modified":"2022-11-11T15:13:25","modified_gmt":"2022-11-11T09:43:25","slug":"solved-why-does-regex-work-well-in-java-but-does-not-work-in-c","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-why-does-regex-work-well-in-java-but-does-not-work-in-c\/","title":{"rendered":"[Solved] Why does regex work well in java, but does not work in c++?"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-55354377\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"55354377\" data-parentid=\"55352800\" data-score=\"1\" data-position-on-page=\"1\" data-highest-scored=\"1\" data-question-has-accepted-highest-score=\"1\" itemprop=\"acceptedAnswer\" itemscope itemtype=\"https:\/\/schema.org\/Answer\">\n<div class=\"post-layout\">\n<div class=\"votecell post-layout--left\"><\/div>\n<div class=\"answercell post-layout--right\">\n<div class=\"s-prose js-post-body\" itemprop=\"text\">\n<p>You are correct.  Your example does not work on Mac OS.  I run into the same problem if I run it on a Mac.<\/p>\n<p>Your final comment asked &#8220;how make it working in MAC OS,pls&#8221;, which I am guessing is asking for the code to make this work on a Mac rather than asking why two regex implementations produce different results.  That is a much easier solution:<\/p>\n<p>This works on my mac:<\/p>\n<pre><code>#include &lt;iostream&gt;\n#include &lt;regex&gt;\n#include &lt;string&gt;\nusing namespace std;\n\nint main() {\n\/\/  std::regex reg(\"[\\\\s\\\\S]*abc[\\\\s\\\\S]*:(\\\\S+)\");\n  std::regex reg(\"[\\\\s\\\\S]*abc.*:(\\\\S+)\");\n  std::string src = \"    abc-def gg, :OK\";\n  std::smatch match;\n  bool flag = std::regex_search(src, match, reg);\n  std::cout &lt;&lt; flag;\n  return 0;\n}\n<\/code><\/pre>\n<p>The same expression that works on regex101.com, does not work on the Mac (llvm).  It seems that the [\\s\\S] does not work well using Mac&#8217;s regex library, but that can be solved by replacing the [\\s\\S] with <code>.*<\/code>.<\/p>\n<p>In response to a further query to isolate the &#8216;OK&#8217; portion of the string, that is done using groups.  The group[0] is always the entire match.  group[1] is the next portion appears between parentheses <code>(...)<\/code><\/p>\n<p>This code illustrates how to extract the two groups.<\/p>\n<pre><code>#include &lt;iostream&gt;\n#include &lt;regex&gt;\n#include &lt;string&gt;\nusing namespace std;\n\nstd::string GetMatch() {\n  \/\/  std::regex reg(\"[\\\\s\\\\S]*abc[\\\\s\\\\S]*:(\\\\S+)\");\n  std::regex reg(\"[\\\\s\\\\S]*abc.*:(\\\\S+)\");\n  std::string src = \"    abc-def gg, :OK\";\n  std::smatch matches;\n  bool flag = std::regex_search(src, matches, reg);\n  std::cout &lt;&lt; flag;\n\n  for(size_t i=0; i&lt;matches.size(); ++i) {\n    cout &lt;&lt; \"MATCH: \" &lt;&lt; matches[i] &lt;&lt; endl;\n  }\n\n  return matches[1];\n}\n\nint main() {\n  std::string result = GetMatch();\n\n\/\/  match\n  cout &lt;&lt; \"The result is \" &lt;&lt; result &lt;&lt; endl;\n  return 0;\n}\n<\/code><\/pre>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">3<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved Why does regex work well in java, but does not work in c++? <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] You are correct. Your example does not work on Mac OS. I run into the same problem if I run it on a Mac. Your final comment asked &#8220;how make it working in MAC OS,pls&#8221;, which I am guessing is asking for the code to make this work on a Mac rather than asking &#8230; <a title=\"[Solved] Why does regex work well in java, but does not work in c++?\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-why-does-regex-work-well-in-java-but-does-not-work-in-c\/\" aria-label=\"More on [Solved] Why does regex work well in java, but does not work in c++?\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[324,323,347],"class_list":["post-20980","post","type-post","status-publish","format-standard","hentry","category-solved","tag-c","tag-java","tag-regex"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.4 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>[Solved] Why does regex work well in java, but does not work in c++? - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-why-does-regex-work-well-in-java-but-does-not-work-in-c\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Why does regex work well in java, but does not work in c++? - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] You are correct. Your example does not work on Mac OS. I run into the same problem if I run it on a Mac. Your final comment asked &#8220;how make it working in MAC OS,pls&#8221;, which I am guessing is asking for the code to make this work on a Mac rather than asking ... 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