{"id":44,"date":"2025-09-19T04:56:28","date_gmt":"2025-09-18T20:56:28","guid":{"rendered":"https:\/\/www.starpoleser.com\/?p=44"},"modified":"2025-09-19T04:59:27","modified_gmt":"2025-09-18T20:59:27","slug":"44","status":"publish","type":"post","link":"https:\/\/www.starpoleser.com\/?p=44","title":{"rendered":"\u601d\u8003\u9898 day 2"},"content":{"rendered":"\n<div class=\"wp-block-jetpack-markdown\"><h2>\u539f\u9898<\/h2>\n<p>\u5b9e\u73b0\u4e00\u4e2a\u7b7e\u540d\u51fd\u6570<em>to_static_str<\/em>\u8ba9\u5b83\u7684\u8fd4\u56de\u503c\u751f\u547d\u5468\u671f\u4e3a <em>&#8216;static<\/em><\/p>\n<pre><code class=\"language-rust\">fn to_static_str(s:String)-&gt;&amp;'static str {\n\n}\nfn main {\n    let s = &quot;xxx&quot;;\n    let s1 = to_static_str(s.clone);\n    assert(s==s1);\n}\n<\/code><\/pre>\n<h2>\u5206\u6790<\/h2>\n<p>\u9996\u5148\uff0c\u770b\u5230\u9898\u76ee\u7b2c\u4e00\u773c\uff0c\u6211\u60f3\u5230\u4e86\u300a\u5723\u7ecf\u300b\u4e2d\u7684\u4e00\u6bb5\u4ee3\u7801\u793a\u4f8b<\/p>\n<pre><code class=\"language-rust\">fn dangle() -&gt; &amp;String { \/\/ dangle \u8fd4\u56de\u4e00\u4e2a\u5b57\u7b26\u4e32\u7684\u5f15\u7528\n\n    let s = String::from(&quot;hello&quot;); \/\/ s \u662f\u4e00\u4e2a\u65b0\u5b57\u7b26\u4e32\n\n    &amp;s \/\/ \u8fd4\u56de\u5b57\u7b26\u4e32 s \u7684\u5f15\u7528\n} \/\/ \u8fd9\u91cc s \u79bb\u5f00\u4f5c\u7528\u57df\u5e76\u88ab\u4e22\u5f03\u3002\u5176\u5185\u5b58\u88ab\u91ca\u653e\u3002\n  \/\/ \u5371\u9669\uff01\n\n<\/code><\/pre>\n<blockquote>\n<p>\u8fd9\u662f\u4e00\u6bb5<em>\u60ac\u5782\u5f15\u7528<\/em>\u7684\u793a\u4f8b\uff0c\u8fd9\u91cc\u6b63\u5e38\u8fd4\u56de\u4e86\u501f\u7528\u7684s\uff0c\u4f46\u662fs\u5728\u51fd\u6570\u7ed3\u675f\u65f6\u5df2\u7ecf\u88ab\u91ca\u653e\u4e86\uff0c\u5982\u679c\u6211\u4eec\u76f4\u63a5\u8fd4\u56des\uff0c\u5c31\u53ef\u4ee5\u6b63\u5e38\u8fd4\u56de\n\u7136\u540e\u6211\u4eec\u7ed3\u5408\u9898\u76ee\uff0c\u5982\u679c\u6211\u4eec\u8fd4\u56des\uff0c\u90a3\u4ed6\u7684\u751f\u547d\u5468\u671f\u4e3a`a\uff0c\u8fd9\u4e0d\u7b26\u5408\u6211\u4eec\u7684\u9700\u6c42<\/p>\n<\/blockquote>\n<p>\u8fd9\u91cc\u6211\u4eec\u5256\u6790\u4e00\u4e0b\u6211\u4eec\u7684\u9700\u6c42\uff0c\u9996\u5148\u5c31\u662f\u6211\u4eec\u9700\u8981\u751f\u547d\u5468\u671f\u4e3a`static\u7684\u8fd4\u56de\u503c\uff0c\u8fd9\u610f\u5473\u7740\u8fd9\u4e2a\u8fd4\u56de\u503c\u7684\u6240\u6709\u6743\u4e0d\u80fd\u79fb\u4ea4\u7ed9\u522b\u4eba\uff0c\u90a3\u6211\u4eec\u5c31\u9700\u8981\u8ba9\u4e0a\u6587\u7684\u60ac\u5782\u5f15\u7528\u5b9e\u73b0\uff0c\u63a5\u4e0b\u6765\u6211\u4eec\u7684\u95ee\u9898\u662f\u5f53\u6211\u4eec <em>&amp;s<\/em>\uff0c\u5b83\u5df2\u7ecf\u88ab\u91ca\u653e\u4e86\uff0c\u7b49\u7b49\uff0c\u5199\u5230\u8fd9\u91cc\uff0c\u6211\u7a81\u7136\u60f3\u5230\u4e86<em>\u53d1\u6563\u51fd\u6570<\/em>\uff0c\u5982\u679c\u6211\u4eec\u5728\u53d1\u6563\u51fd\u6570\u4e2d\u501f\u7528\u4e86s\uff0c\u662f\u5426\u610f\u5473\u7740s\u7684\u751f\u547d\u5468\u671f\u53d1\u751f\u6539\u53d8\uff1f\u8ba9\u6211\u4eec\u8bd5\u8bd5<\/p>\n<pre><code class=\"language-rust\">fn forever(s2:String) -&gt; !{\n    loop {\n        &amp;s2;\n    };\n}\nfn to_static_str(s:String)-&gt;&amp;'static str {\n    forever(s);\n    &amp;s\n}\nfn main() {\n    let s = &quot;xxx&quot;;\n    let s1 = s.clone();\n    let s2 = to_static_str(s1.to_string());\n    assert_eq!(s,s1);\n}\n<\/code><\/pre>\n<h2>\u603b\u7ed3<\/h2>\n<p>\u7ed3\u679c\u662f\u8fd9\u4e2a\u4ee3\u7801\u62a5\u4e86\u4e00\u5806warning\u7136\u540e\u5e94\u8be5\u662f\u7f16\u8bd1\u4e0d\u51fa\u6765\uff0c\u6211\u8fd8\u662f\u518d\u591a\u5b66\u5b66\u518d\u7814\u7a76\u8fd9\u4e2a\u5427<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-44","post","type-post","status-publish","format-standard","hentry","category-rust"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.starpoleser.com\/index.php?rest_route=\/wp\/v2\/posts\/44","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.starpoleser.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.starpoleser.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.starpoleser.com\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.starpoleser.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=44"}],"version-history":[{"count":2,"href":"https:\/\/www.starpoleser.com\/index.php?rest_route=\/wp\/v2\/posts\/44\/revisions"}],"predecessor-version":[{"id":47,"href":"https:\/\/www.starpoleser.com\/index.php?rest_route=\/wp\/v2\/posts\/44\/revisions\/47"}],"wp:attachment":[{"href":"https:\/\/www.starpoleser.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=44"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.starpoleser.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=44"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.starpoleser.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=44"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}