{"id":245,"date":"2012-05-16T16:24:05","date_gmt":"2012-05-16T16:24:05","guid":{"rendered":"0266e33d3f546cb5436a10798e657d97"},"modified":"2012-05-16T16:24:05","modified_gmt":"2012-05-16T16:24:05","slug":"","status":"publish","type":"post","link":"https:\/\/www.xiaobo.li\/notes\/archives\/245","title":{"rendered":"c# \u56db\u820d\u4e94\u5165"},"content":{"rendered":"<div id=\"cnblogs_post_body\">\n<div id=\"cnblogs_post_body\">\n<p>C# \u4e2d\u6ca1\u6709\u56db\u820d\u4e94\u5165\u51fd\u6570\uff0c\u7a0b\u5e8f\u8bed\u8a00\u90fd\u6ca1\u6709\u56db\u820d\u4e94\u5165\u51fd\u6570\uff0c\u56e0\u4e3a\u56db\u820d\u4e94\u5165\u7b97\u6cd5\u4e0d\u79d1\u5b66\uff0c\u56fd\u9645\u901a\u884c\u7684\u662f Banker \u820d\u5165\u6cd5<\/p>\n<p>Bankers rounding\uff08\u94f6\u884c\u5bb6\u820d\u5165\uff09\u7b97\u6cd5\uff0c\u5373\u56db\u820d\u516d\u5165\u4e94\u53d6\u5076\u3002\u4e8b\u5b9e\u4e0a\u8fd9\u4e5f\u662f IEEE \u89c4\u5b9a\u7684\u820d\u5165\u6807\u51c6\u3002\u56e0\u6b64\u6240\u6709\u7b26\u5408 IEEE \u6807\u51c6\u7684\u8bed\u8a00\u90fd\u5e94\u8be5\u662f\u91c7\u7528\u8fd9\u4e00\u7b97\u6cd5\u7684<\/p>\n<p>Math.Round \u65b9\u6cd5\u9ed8\u8ba4\u7684\u4e5f\u662f Banker \u820d\u5165\u6cd5<\/p>\n<p>\u5728 .NET 2.0 \u4e2d Math.Round \u65b9\u6cd5\u6709\u51e0\u4e2a\u91cd\u8f7d\u65b9\u6cd5<br \/>\nMath.Round(Decimal, MidpointRounding)<br \/>\nMath.Round(Double, MidpointRounding)<br \/>\nMath.Round(Decimal, Int32, MidpointRounding)<br \/>\nMath.Round(Double, Int32, MidpointRounding)<\/p>\n<p>\u5c06\u5c0f\u6570\u503c\u820d\u5165\u5230\u6307\u5b9a\u7cbe\u5ea6\u3002MidpointRounding \u53c2\u6570\uff0c\u6307\u5b9a\u5f53\u4e00\u4e2a\u503c\u6b63\u597d\u5904\u4e8e\u53e6\u4e24\u4e2a\u6570\u4e2d\u95f4\u65f6\u5982\u4f55\u820d\u5165\u8fd9\u4e2a\u503c<\/p>\n<p>\u8be5\u53c2\u6570\u662f\u4e2a MidpointRounding \u679a\u4e3e<\/p>\n<p>\u6b64\u679a\u4e3e\u6709\u4e24\u4e2a\u6210\u5458\uff0cMSDN \u4e2d\u7684\u8bf4\u660e\u662f\uff1a<br \/>\nAwayFromZero \u5f53\u4e00\u4e2a\u6570\u5b57\u662f\u5176\u4ed6\u4e24\u4e2a\u6570\u5b57\u7684\u4e2d\u95f4\u503c\u65f6\uff0c\u4f1a\u5c06\u5176\u820d\u5165\u4e3a\u4e24\u4e2a\u503c\u4e2d\u7edd\u5bf9\u503c\u8f83\u5c0f\u7684\u503c\u3002<br \/>\nToEven \u5f53\u4e00\u4e2a\u6570\u5b57\u662f\u5176\u4ed6\u4e24\u4e2a\u6570\u5b57\u7684\u4e2d\u95f4\u503c\u65f6\uff0c\u4f1a\u5c06\u5176\u820d\u5165\u4e3a\u6700\u63a5\u8fd1\u7684\u5076\u6570\u3002<\/p>\n<p>\u6ce8 \u610f\uff01\u8fd9\u91cc\u5173\u4e8e MidpointRounding.AwayFromZero \u7684\u8bf4\u660e\u662f\u9519\u8bef\u7684\uff01\u5b9e\u9645\u820d\u5165\u4e3a\u4e24\u4e2a\u503c\u4e2d\u7edd\u5bf9\u503c\u8f83\u5927\u7684\u503c\u3002\u4e0d\u8fc7 MSDN \u4e2d\u7684 \u4f8b\u5b50\u662f\u6b63\u786e\u7684\uff0c\u82f1\u6587\u63cf\u8ff0\u539f\u6587\u662f it is rounded toward the nearest number that is away from zero.<\/p>\n<p>\u6240\u4ee5\uff0c\u8981\u5b9e\u73b0\u56db\u820d\u4e94\u5165\u51fd\u6570\uff0c\u5bf9\u4e8e\u6b63\u6570\uff0c\u53ef\u4ee5\u52a0\u4e00\u4e2a MidpointRounding.AwayFromZero \u53c2\u6570\u6307\u5b9a\u5f53\u4e00\u4e2a\u6570\u5b57\u662f\u5176\u4ed6\u4e24\u4e2a\u6570\u5b57\u7684\u4e2d\u95f4\u503c\u65f6\u5176\u820d\u5165\u4e3a\u4e24\u4e2a\u503c\u4e2d\u7edd\u5bf9\u503c\u8f83\u5927\u7684\u503c\uff0c\u4f8b\uff1a<\/p>\n<p>Math.Round(3.45, 2, MidpointRounding.AwayFromZero)<\/p>\n<p>\u4e0d\u8fc7\u5bf9\u4e8e\u8d1f\u6570\u4e0a\u9762\u7684\u65b9\u6cd5\u5c31\u53c8\u4e0d\u5bf9\u4e86<\/p>\n<p>\u56e0\u6b64\u9700\u8981\u81ea\u5df1\u5199\u4e2a\u51fd\u6570\u6765\u5904\u7406<br \/>\n\u7b2c\u4e00\u4e2a\u51fd\u6570\uff1a<br \/>\ndouble Round(double value, int decimals)<br \/>\n{<br \/>\n\u3000\u3000if (value &lt; 0)<br \/>\n\u3000\u3000{<br \/>\n\u3000\u3000\u3000\u3000return Math.Round(value + 5 \/ Math.Pow(10, decimals + 1), decimals, MidpointRounding.AwayFromZero);<br \/>\n\u3000\u3000}<br \/>\n\u3000\u3000else<br \/>\n\u3000\u3000{<br \/>\n\u3000\u3000\u3000\u3000return Math.Round(value, decimals, MidpointRounding.AwayFromZero);<br \/>\n\u3000\u3000}<br \/>\n} <\/p>\n<p><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u7b2c\u4e8c\u4e2a\u51fd\u6570\uff1a<br \/>\ndouble Round(double d, int i)<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>{<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000if(d &gt;=0)<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000{<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000\u3000\u3000d += 5 * Math.Pow(10, -(i + 1));<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000}<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000else<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000{<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000\u3000\u3000d += -5 * Math.Pow(10, -(i + 1));<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000}<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000string str = d.ToString();<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000string[] strs = str.Split('.');<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000int idot = str.IndexOf('.');<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000string prestr = strs[0];<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000string poststr = strs[1];<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000if(poststr.Length &gt; i)<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000{<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000\u3000\u3000poststr = str.Substring(idot + 1, i);<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000}<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000string strd = prestr + \".\" + poststr;<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000d = Double.Parse(strd);<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>\u3000\u3000return d;<br \/>\n<wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr><wbr><\/wbr>}<\/p>\n<p>\u53c2\u6570\uff1ad\u8868\u793a\u8981\u56db\u820d\u4e94\u5165\u7684\u6570\uff1bi\u8868\u793a\u8981\u4fdd\u7559\u7684\u5c0f\u6570\u70b9\u540e\u4e3a\u6570\u3002<\/p>\n<p>\u5176\u4e2d\u7b2c\u4e8c\u79cd\u65b9\u6cd5\u662f\u6b63\u8d1f\u6570\u90fd\u56db\u820d\u4e94\u5165\uff0c\u7b2c\u4e00\u79cd\u65b9\u6cd5\u662f\u6b63\u6570\u56db\u820d\u4e94\u5165\uff0c\u8d1f\u6570\u662f\u4e94\u820d\u516d\u5165\u3002<\/p>\n<p>\u5907\u6ce8\uff1a\u4e2a\u4eba\u8ba4\u4e3a\u7b2c\u4e00\u79cd\u65b9\u6cd5\u9002\u5408\u5904\u7406\u8d27\u5e01\u8ba1\u7b97\uff0c\u800c\u7b2c\u4e8c\u79cd\u65b9\u6cd5\u9002\u5408\u6570\u636e\u7edf\u8ba1\u7684\u663e\u793a\u3002<\/p>\n<\/div>\n<p>\n<script type=\"text\/javascript\"><\/script>\n<\/p>\n<p>\n<script type=\"text\/javascript\">\/\/ <![CDATA[\n\u8f6c\u8f7d\u81ea\uff1a<a href=\"http:\/\/hjly2007.blog.163.com\/blog\/static\/245706932009330102357900\/\" _mce_href=\"http:\/\/hjly2007.blog.163.com\/blog\/static\/245706932009330102357900\/\">http:\/\/hjly2007.blog.163.com\/blog\/static\/245706932009330102357900\/<\/a> \/\/ ]]><\/script>\n<\/p>\n<\/div>\n<div id=\"MySignature\"><\/div>\n<p><script type=\"text\/javascript\">\nvar isLogined = false;\nvar cb_blogId = 88548;\nvar cb_entryId = 2094735;\nvar cb_blogApp = currentBlogApp;\nvar cb_blogUserGuid = \"8d52cd80-6d3d-e011-ac81-842b2b196315\";\nvar cb_entryCreatedDate = '2011\/6\/30 15:59:00';\nvar enableGoogleAd = true;\nvar googletag = googletag || {};\ngoogletag.cmd = googletag.cmd || [];\n<\/script><\/p>\n<div id=\"blog_post_info_block\">\n<div id=\"blog_post_info\">\n<div id=\"BlogPostCategory\">&nbsp;<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<div id=\"cnblogs_post_body\">\n<div id=\"cnblogs_post_body\">\n<p>C# \u4e2d\u6ca1\u6709\u56db\u820d\u4e94\u5165\u51fd\u6570\uff0c\u7a0b\u5e8f\u8bed\u8a00\u90fd\u6ca1\u6709\u56db\u820d\u4e94\u5165\u51fd\u6570\uff0c\u56e0\u4e3a\u56db\u820d\u4e94\u5165\u7b97\u6cd5\u4e0d\u79d1\u5b66\uff0c\u56fd\u9645\u901a\u884c\u7684\u662f Banker \u820d\u5165\u6cd5<\/p>\n<p>Bankers rounding\uff08\u94f6\u884c\u5bb6\u820d\u5165\uff09\u7b97\u6cd5\uff0c\u5373\u56db\u820d\u516d\u5165\u4e94\u53d6\u5076\u3002\u4e8b\u5b9e\u4e0a\u8fd9\u4e5f\u662f IEEE \u89c4\u5b9a\u7684\u820d\u5165\u6807\u51c6\u3002\u56e0\u6b64\u6240\u6709\u7b26\u5408 IEEE \u6807\u51c6\u7684\u8bed\u8a00\u90fd\u5e94\u8be5\u662f\u91c7\u7528\u8fd9\u4e00\u7b97\u6cd5\u7684<\/p>\n<p>Math.Round \u65b9\u6cd5\u9ed8\u8ba4\u7684\u4e5f\u662f Banker \u820d\u5165\u6cd5<\/p>\n<p>\u5728 .NET 2.0 \u4e2d Math.Round \u65b9\u6cd5\u6709\u51e0\u4e2a\u91cd\u8f7d\u65b9\u6cd5<br \/>\nMath.Round(Decimal, MidpointRounding)<br \/>\nMath.Round(Double, MidpointRounding)<br \/>\nMath.Round(Dec...<\/p>\n<\/div>\n<\/div>\n<p> <a href=\"https:\/\/www.xiaobo.li\/notes\/archives\/245\">\u7ee7\u7eed\u9605\u8bfb <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[273],"tags":[16],"class_list":["post-245","post","type-post","status-publish","format-standard","hentry","category-article","tag-C"],"_links":{"self":[{"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/posts\/245","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/comments?post=245"}],"version-history":[{"count":0,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/posts\/245\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/media?parent=245"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/categories?post=245"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/tags?post=245"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}