{"id":309,"date":"2020-05-09T17:19:46","date_gmt":"2020-05-09T09:19:46","guid":{"rendered":"https:\/\/wp.dj47.top\/?p=309"},"modified":"2021-10-20T16:16:18","modified_gmt":"2021-10-20T08:16:18","slug":"unset%e9%94%80%e6%af%81%e5%8f%98%e9%87%8f%e5%b9%b6%e9%87%8a%e6%94%be%e5%86%85%e5%ad%98%e9%97%ae%e9%a2%98","status":"publish","type":"post","link":"https:\/\/www.djlog.cn\/?p=309","title":{"rendered":"unset\u9500\u6bc1\u53d8\u91cf\u5e76\u91ca\u653e\u5185\u5b58\u95ee\u9898"},"content":{"rendered":"<p style=\"box-sizing: border-box; margin: 10px auto; color: #333333; font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; font-size: 13px; text-align: justify; background-color: #ffffff;\">PHP\u7684unset()\u51fd\u6570\u7528\u6765\u6e05\u9664\u3001\u9500\u6bc1\u53d8\u91cf\uff0c\u4e0d\u7528\u7684\u53d8\u91cf\uff0c\u6211\u4eec\u53ef\u4ee5\u7528unset()\u5c06\u5b83\u9500\u6bc1\u3002\u4f46\u662f\u67d0\u4e9b\u65f6\u5019\uff0c\u7528unset()\u5374\u65e0\u6cd5\u8fbe\u5230\u9500\u6bc1\u53d8 \u91cf\u5360\u7528\u7684\u5185\u5b58\uff01\u6211\u4eec\u5148\u770b\u4e00\u4e2a\u4f8b\u5b50\uff1a<\/p>\n<pre class=\"language-php\"><code>&lt;?php\r\n$s=str_repeat('1',255); \/\/\u4ea7\u751f\u7531255\u4e2a1\u7ec4\u6210\u7684\u5b57\u7b26\u4e32\r\n$m=memory_get_usage(); \/\/\u83b7\u53d6\u5f53\u524d\u5360\u7528\u5185\u5b58\r\nunset($s);\r\n$mm=memory_get_usage(); \/\/unset()\u540e\u518d\u67e5\u770b\u5f53\u524d\u5360\u7528\u5185\u5b58\r\necho $m-$mm;\r\n?&gt;<\/code><\/pre>\n<p style=\"box-sizing: border-box; margin: 10px auto; color: #333333; font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; font-size: 13px; text-align: justify; background-color: #ffffff;\">\u6700\u540e\u8f93\u51faunset()\u4e4b\u524d\u5360\u7528\u5185\u5b58\u51cf\u53bbunset()\u4e4b\u540e\u5360\u7528\u5185\u5b58\uff0c\u5982\u679c\u662f\u6b63\u6570\uff0c\u90a3\u4e48\u8bf4\u660eunset($s)\u5df2\u7ecf\u5c06$s\u4ece\u5185\u5b58\u4e2d\u9500\u6bc1(\u6216\u8005\u8bf4\uff0cunset()\u4e4b\u540e\u5185\u5b58\u5360\u7528\u51cf\u5c11\u4e86)\uff0c\u53ef\u662f\u6211\u5728PHP5\u548cwindows\u5e73\u53f0\u4e0b\uff0c\u5f97\u5230\u7684\u7ed3\u679c\u662f\uff1a0\u3002\u8fd9\u662f\u5426\u53ef\u4ee5\u8bf4\u660e\uff0cunset($s)\u5e76\u6ca1\u6709\u8d77 \u5230\u9500\u6bc1\u53d8\u91cf$s\u6240\u5360\u7528\u5185\u5b58\u7684\u4f5c\u7528\u5462\uff1f\u6211\u4eec\u518d\u4f5c\u4e0b\u9762\u7684\u4f8b\u5b50\uff1a<\/p>\n<pre class=\"language-php\"><code>&lt;?php\r\n$s=str_repeat('1',256); \/\/\u4ea7\u751f\u7531256\u4e2a1\u7ec4\u6210\u7684\u5b57\u7b26\u4e32\r\n$m=memory_get_usage(); \/\/\u83b7\u53d6\u5f53\u524d\u5360\u7528\u5185\u5b58\r\nunset($s);\r\n$mm=memory_get_usage(); \/\/unset()\u540e\u518d\u67e5\u770b\u5f53\u524d\u5360\u7528\u5185\u5b58\r\necho $m-$mm;\r\n?&gt;<\/code><\/pre>\n<p style=\"box-sizing: border-box; margin: 10px auto; color: #333333; font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; font-size: 13px; text-align: justify; background-color: #ffffff;\">\u8fd9\u4e2a\u4f8b\u5b50\uff0c\u548c\u4e0a\u9762\u7684\u4f8b\u5b50\u51e0\u4e4e\u76f8\u540c\uff0c\u552f\u4e00\u7684\u4e0d\u540c\u662f\uff0c$s\u7531256\u4e2a1\u7ec4\u6210\uff0c\u5373\u6bd4\u7b2c\u4e00\u4e2a\u4f8b\u5b50\u591a\u4e86\u4e00\u4e2a1\uff0c\u5f97\u5230\u7ed3\u679c\u662f\uff1a272\u3002\u8fd9\u662f\u5426\u53ef\u4ee5\u8bf4 \u660e\uff0cunset($s)\u5df2\u7ecf\u5c06$s\u6240\u5360\u7528\u7684\u5185\u5b58\u9500\u6bc1\u4e86\uff1f<br style=\"box-sizing: border-box;\" \/>\u901a\u8fc7\u4e0a\u9762\u4e24\u4e2a\u4f8b\u5b50\uff0c\u6211\u4eec\u53ef\u4ee5\u5f97\u51fa\u4ee5\u4e0b\u7ed3\u8bba\uff1a<br style=\"box-sizing: border-box;\" \/>\u7ed3\u8bba\u4e00\u3001<span style=\"box-sizing: border-box; font-weight: bold;\">unset()\u51fd\u6570\u53ea\u80fd\u5728\u53d8\u91cf\u503c\u5360\u7528\u5185\u5b58\u7a7a\u95f4\u8d85\u8fc7256\u5b57\u8282\u65f6\u624d\u4f1a\u91ca\u653e\u5185\u5b58\u7a7a\u95f4\u3002<\/span><\/p>\n<p style=\"box-sizing: border-box; margin: 10px auto; color: #333333; font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; font-size: 13px; text-align: justify; background-color: #ffffff;\">\u90a3\u4e48\u662f\u4e0d\u662f\u53ea\u8981\u53d8\u91cf\u503c\u8d85\u8fc7256\uff0c\u4f7f\u7528unset\u5c31\u53ef\u4ee5\u91ca\u653e\u5185\u5b58\u7a7a\u95f4\u5462\uff1f\u6211\u4eec\u518d\u901a\u8fc7\u4e00\u4e2a\u4f8b\u5b50\u6765\u6d4b\u8bd5\u4e00\u4e0b\uff1a<\/p>\n<pre class=\"language-php\"><code>&lt;?php\r\n$s=str_repeat('1',256); \/\/\u8fd9\u548c\u7b2c\u4e8c\u4e2a\u4f8b\u5b50\u5b8c\u5168\u76f8\u540c\r\n$p=&amp;$s;\r\n$m=memory_get_usage();\r\nunset($s); \/\/\u9500\u6bc1$s\r\n$mm=memory_get_usage();\r\necho $p.'&lt;br \/&gt;';\r\necho $m-$mm;\r\n?&gt;<\/code><\/pre>\n<p style=\"box-sizing: border-box; margin: 10px auto; color: #333333; font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; font-size: 13px; text-align: justify; background-color: #ffffff;\">\u5237\u65b0\u9875\u9762\uff0c\u6211\u4eec\u770b\u5230\u7b2c\u4e00\u884c\u6709256\u4e2a1\uff0c\u7b2c\u4e8c\u884c\u662f0\uff0c\u6309\u7406\u8bf4\u6211\u4eec\u5df2\u7ecf\u9500\u6bc1\u4e86$s\uff0c\u800c$p\u53ea\u662f\u5f15\u7528$s\u7684\u53d8\u91cf\uff0c\u5e94\u8be5\u662f\u6ca1\u6709\u5185\u5bb9\u4e86\uff0c\u53e6 \u5916\uff0cunset($s)\u524d\u540e\u5185\u5b58\u5360\u7528\u6ca1\u53d8\u5316\uff01\u73b0\u5728\u6211\u4eec\u518d\u505a\u4ee5\u4e0b\u7684\u4f8b\u5b50\uff1a<\/p>\n<pre class=\"language-php\"><code>&lt;?php\r\n$s=str_repeat('1',256); \/\/\u8fd9\u548c\u7b2c\u4e8c\u4e2a\u4f8b\u5b50\u5b8c\u5168\u76f8\u540c\r\n$p=&amp;$s;\r\n$m=memory_get_usage();\r\n$s=null; \/\/\u8bbe\u7f6e$s\u4e3anull\r\n$mm=memory_get_usage();\r\necho $p.'&lt;br \/&gt;';\r\necho $m-$mm;\r\n?&gt;<\/code><\/pre>\n<p style=\"box-sizing: border-box; margin: 10px auto; color: #333333; font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; font-size: 13px; text-align: justify; background-color: #ffffff;\">\u73b0\u5728\u5237\u65b0\u9875\u9762\uff0c\u6211\u4eec\u770b\u5230\uff0c\u8f93\u51fa$p\u5df2\u7ecf\u662f\u6ca1\u6709\u5185\u5bb9\u4e86\uff0cunset()\u524d\u540e\u5185\u5b58\u5360\u7528\u91cf\u4e4b\u5dee\u662f272\uff0c\u5373\u5df2\u7ecf\u6e05\u9664\u4e86\u53d8\u91cf\u5360\u7528\u7684\u5185\u5b58\u3002\u672c\u4f8b\u4e2d\u7684$s=null\u4e5f \u53ef\u4ee5\u6362\u6210unset()\uff0c\u5982\u4e0b\uff1a<\/p>\n<pre class=\"language-php\"><code>&lt;?php\r\n$s=str_repeat('1',256); \/\/\u8fd9\u548c\u7b2c\u4e8c\u4e2a\u4f8b\u5b50\u5b8c\u5168\u76f8\u540c\r\n$p=&amp;$s;\r\n$m=memory_get_usage();\r\nunset($s); \/\/\u9500\u6bc1$s\r\nunset($p);\r\n$mm=memory_get_usage();\r\necho $p.'&lt;br \/&gt;';\r\necho $m-$mm;\r\n?&gt;<\/code><\/pre>\n<p style=\"box-sizing: border-box; margin: 10px auto; color: #333333; font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; font-size: 13px; text-align: justify; background-color: #ffffff;\">\u6211\u4eec\u5c06$s\u548c$p\u90fd\u4f7f\u7528unset()\u9500\u6bc1\uff0c\u8fd9\u65f6\u518d\u770b\u5185\u5b58\u5360\u7528\u91cf\u4e4b\u5dee\u4e5f\u662f272\uff0c\u8bf4\u660e\u8fd9\u6837\u4e5f\u53ef\u4ee5\u91ca\u653e\u5185\u5b58\u3002\u90a3\u4e48\uff0c\u6211\u4eec\u53ef\u4ee5\u5f97\u5230\u53e6\u5916\u4e00\u6761\u7ed3\u8bba\uff1a<br style=\"box-sizing: border-box;\" \/>\u7ed3\u8bba\u4e8c\u3001\u53ea<span style=\"box-sizing: border-box; font-weight: bold;\">\u6709\u5f53\u6307\u5411\u8be5\u53d8\u91cf\u7684\u6240\u6709\u53d8\u91cf\uff08\u5982\u5f15\u7528\u53d8\u91cf\uff09\u90fd\u88ab\u9500\u6bc1\u540e\uff0c\u624d\u4f1a\u91ca\u653e\u5185\u5b58\u3002<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>PHP\u7684unset()\u51fd\u6570\u7528\u6765\u6e05\u9664\u3001\u9500\u6bc1\u53d8\u91cf\uff0c\u4e0d\u7528\u7684\u53d8\u91cf\uff0c\u6211\u4eec\u53ef\u4ee5\u7528unset()\u5c06\u5b83\u9500\u6bc1\u3002\u4f46\u662f\u67d0\u4e9b\u65f6\u5019\uff0c\u7528u [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[4],"tags":[],"class_list":["post-309","post","type-post","status-publish","format-standard","hentry","category-php"],"_links":{"self":[{"href":"https:\/\/www.djlog.cn\/index.php?rest_route=\/wp\/v2\/posts\/309","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.djlog.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.djlog.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.djlog.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.djlog.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=309"}],"version-history":[{"count":0,"href":"https:\/\/www.djlog.cn\/index.php?rest_route=\/wp\/v2\/posts\/309\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.djlog.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=309"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.djlog.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=309"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.djlog.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=309"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}