{"id":2810,"date":"2017-10-27T22:12:24","date_gmt":"2017-10-27T14:12:24","guid":{"rendered":"http:\/\/cn.hostease.com\/xueyuan\/?p=2810"},"modified":"2017-10-27T22:12:24","modified_gmt":"2017-10-27T14:12:24","slug":"%e8%a7%a3%e5%86%b3php%e6%b5%ae%e7%82%b9%e6%95%b0%ef%bc%88%e5%b0%8f%e6%95%b0%ef%bc%89%e8%bf%90%e7%ae%97%e9%94%99%e8%af%af%e7%9a%84bug","status":"publish","type":"post","link":"https:\/\/cn.hostease.com\/xueyuan\/jishu\/chengxujiaoben\/php\/%e8%a7%a3%e5%86%b3php%e6%b5%ae%e7%82%b9%e6%95%b0%ef%bc%88%e5%b0%8f%e6%95%b0%ef%bc%89%e8%bf%90%e7%ae%97%e9%94%99%e8%af%af%e7%9a%84bug\/","title":{"rendered":"\u89e3\u51b3php\u6d6e\u70b9\u6570\uff08\u5c0f\u6570\uff09\u8fd0\u7b97\u9519\u8bef\u7684bug"},"content":{"rendered":"
bc\u662fBinary Calculator\u7684\u7f29\u5199\u3002bc*\u51fd\u6570\u7684\u53c2\u6570\u90fd\u662f\u64cd\u4f5c\u6570\u52a0\u4e0a\u4e00\u4e2a\u53ef\u9009\u7684 [int scale]\uff0c\u6bd4\u5982string bcadd(string $left_operand, string $right_operand[, int $scale])\uff0c\u5982\u679cscale\u6ca1\u6709\u63d0\u4f9b\uff0c\u5c31\u7528bcscale\u7684\u7f3a\u7701\u503c\u3002\u8fd9\u91cc\u5927\u6570\u76f4\u63a5\u7528\u4e00\u4e2a\u75310-9\u7ec4\u6210\u7684string\u8868\u793a\uff0c\u8ba1\u7b97\u7ed3\u679c\u8fd4\u56de\u7684\u4e5f\u662f\u4e00\u4e2a string\u3002<\/span>
\nbcadd \u2014 \u5c06\u4e24\u4e2a\u9ad8\u7cbe\u5ea6\u6570\u5b57\u76f8\u52a0 <\/span>
\nbccomp \u2014 \u6bd4\u8f83\u4e24\u4e2a\u9ad8\u7cbe\u5ea6\u6570\u5b57\uff0c\u8fd4\u56de-1, 0, 1 <\/span>
\nbcdiv \u2014 \u5c06\u4e24\u4e2a\u9ad8\u7cbe\u5ea6\u6570\u5b57\u76f8\u9664 <\/span>
\nbcmod \u2014 \u6c42\u9ad8\u7cbe\u5ea6\u6570\u5b57\u4f59\u6570 <\/span>
\nbcmul \u2014 \u5c06\u4e24\u4e2a\u9ad8\u7cbe\u5ea6\u6570\u5b57\u76f8\u4e58 <\/span>
\nbcpow \u2014 \u6c42\u9ad8\u7cbe\u5ea6\u6570\u5b57\u4e58\u65b9 <\/span>
\nbcpowmod \u2014 \u6c42\u9ad8\u7cbe\u5ea6\u6570\u5b57\u4e58\u65b9\u6c42\u6a21\uff0c\u6570\u8bba\u91cc\u975e\u5e38\u5e38\u7528 <\/span>
\nbcscale \u2014 \u914d\u7f6e\u9ed8\u8ba4\u5c0f\u6570\u70b9\u4f4d\u6570\uff0c\u76f8\u5f53\u4e8e\u5c31\u662fLinux bc\u4e2d\u7684\u201dscale=\u201d <\/span>
\nbcsqrt \u2014 \u6c42\u9ad8\u7cbe\u5ea6\u6570\u5b57\u5e73\u65b9\u6839 <\/span>
\nbcsub \u2014 \u5c06\u4e24\u4e2a\u9ad8\u7cbe\u5ea6\u6570\u5b57\u76f8\u51cf<\/span>
\n
\n\u9996\u5148\u770b\u4e00\u6bb5\u4ee3\u7801:<\/span>
\n<?php<\/span>
\n$a = 0.1;<\/span>
\n$b = 0.7;<\/span>
\nvar_dump(($a + $b) == 0.8);<\/span><\/p>\n

\u6253\u5370\u51fa\u6765\u7684\u503c\u5c45\u7136\u4e3a boolean false<\/span>
\n\u8fd9\u662f\u4e3a\u5565?PHP\u624b\u518c\u5bf9\u4e8e\u6d6e\u70b9\u6570\u6709\u4ee5\u4e0b\u8b66\u544a\u4fe1\u606f:<\/span>
\nWarning <\/span>
\n\u6d6e\u70b9\u6570\u7cbe\u5ea6<\/span>
\n\u663e\u7136\u7b80\u5355\u7684\u5341\u8fdb\u5236\u5206\u6570\u5982\u540c 0.1 \u6216 0.7 \u4e0d\u80fd\u5728\u4e0d\u4e22\u5931\u4e00\u70b9\u70b9\u7cbe\u5ea6\u7684\u60c5\u51b5\u4e0b\u8f6c\u6362\u4e3a\u5185\u90e8\u4e8c\u8fdb\u5236\u7684\u683c\u5f0f\u3002\u8fd9\u5c31\u4f1a\u9020\u6210\u6df7\u4e71\u7684\u7ed3\u679c\uff1a\u4f8b\u5982\uff0cfloor((0.1+0.7)*10) \u901a\u5e38\u4f1a\u8fd4\u56de 7 \u800c\u4e0d\u662f\u9884\u671f\u4e2d\u7684 8\uff0c\u56e0\u4e3a\u8be5\u7ed3\u679c\u5185\u90e8\u7684\u8868\u793a\u5176\u5b9e\u662f\u7c7b\u4f3c 7.9999999999…\u3002 <\/span>
\n\u8fd9\u548c\u4e00\u4e2a\u4e8b\u5b9e\u6709\u5173\uff0c\u90a3\u5c31\u662f\u4e0d\u53ef\u80fd\u7cbe\u786e\u7684\u7528\u6709\u9650\u4f4d\u6570\u8868\u8fbe\u67d0\u4e9b\u5341\u8fdb\u5236\u5206\u6570\u3002\u4f8b\u5982\uff0c\u5341\u8fdb\u5236\u7684 1\/3 \u53d8\u6210\u4e86 0.3333333. . .\u3002 <\/span>
\n\u6240\u4ee5\u6c38\u8fdc\u4e0d\u8981\u76f8\u4fe1\u6d6e\u70b9\u6570\u7ed3\u679c\u7cbe\u786e\u5230\u4e86\u6700\u540e\u4e00\u4f4d\uff0c\u4e5f\u6c38\u8fdc\u4e0d\u8981\u6bd4\u8f83\u4e24\u4e2a\u6d6e\u70b9\u6570\u662f\u5426\u76f8\u7b49\u3002\u5982\u679c\u786e\u5b9e\u9700\u8981\u66f4\u9ad8\u7684\u7cbe\u5ea6\uff0c\u5e94\u8be5\u4f7f\u7528\u4efb\u610f\u7cbe\u5ea6\u6570\u5b66\u51fd\u6570\u6216\u8005 gmp \u51fd\u6570<\/span>
\n\u90a3\u4e48\u4e0a\u9762\u7684\u7b97\u5f0f\u6211\u4eec\u5e94\u8be5\u6539\u5199\u4e3a<\/span><\/p>\n

<?php<\/span>
\n$a = 0.1;<\/span>
\n$b = 0.7;<\/span>
\nvar_dump(bcadd($a,$b,2) == 0.8);<\/span><\/p>\n

\u8fd9\u6837\u5c31\u80fd\u89e3\u51b3\u6d6e\u70b9\u6570\u7684\u8ba1\u7b97\u95ee\u9898\u4e86<\/span><\/p>\n

\u53e6\u5916\uff0c\u8fd8\u53ef\u4ee5\u4f7f\u7528round() \u51fd\u6570\u5904\u7406\u4e00\u4e0b\uff1a<\/span>
\n<\/span>
\n<?php<\/span>
\necho ceil( round((2.1\/0.7),1) );<\/span><\/p>\n

\u867d\u7136 round() \u51fd\u6570\u662f\u6309\u7167\u6307\u5b9a\u7684\u7cbe\u5ea6\u8fdb\u884c\u56db\u820d\u4e94\u5165\uff0c\u4f46\u4fdd\u7559\u5c0f\u6570\u70b9\u540e\u4e00\u4f4d\uff0c\u5bf9\u6211\u4eec\u7684\u53d6\u6574\u7ed3\u679c\u662f\u6ca1\u5f71\u54cd\u7684\u3002<\/span><\/div>\n

<\/div>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

bc\u662fBinary Calculator\u7684\u7f29\u5199\u3002bc*\u51fd\u6570\u7684\u53c2\u6570\u90fd\u662f\u64cd\u4f5c\u6570\u52a0\u4e0a\u4e00\u4e2a\u53ef\u9009\u7684 [int scale … \u9605\u8bfb\u66f4\u591a<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[6],"tags":[369],"class_list":["post-2810","post","type-post","status-publish","format-standard","hentry","category-php","tag-php"],"aioseo_notices":[],"jetpack_featured_media_url":"","jetpack-related-posts":[],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/posts\/2810","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/comments?post=2810"}],"version-history":[{"count":1,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/posts\/2810\/revisions"}],"predecessor-version":[{"id":2811,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/posts\/2810\/revisions\/2811"}],"wp:attachment":[{"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/media?parent=2810"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/categories?post=2810"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/tags?post=2810"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}