{"rsdb":{"rid":"239252","subhead":"","postdate":"0","aid":"164909","fid":"85","uid":"1","topic":"1","content":"
\n

java<\/a> script<\/h3> \n

0.1 + 0.2 \u4e3a\u5565\u4e0d\u7b49\u4e8e 0.3 ? \uff08\u6b63\u786e\u7ed3\u679c\uff1a0.30000000000000004\uff09<\/p> \n

0.8 * 7 \u4e3a\u5565\u4e0d\u7b49\u4e8e 5.6 ? \uff08\u6b63\u786e\u7ed3\u679c\uff1a5.6000000000000005\uff09<\/p> \n

PHP<\/h3> \n

var_dump(intval(0.58 * 100));<\/p> \n

\u6b63\u786e\u7ed3\u679c\u662f 57\uff0c\u800c\u4e0d\u662f 58<\/p> \n

\u6d6e\u70b9\u8fd0\u7b97\u60f9\u7684\u7978<\/h3> \n

\u5176\u5b9e\u8fd9\u4e9b\u7ed3\u679c\u90fd\u5e76\u975e\u8bed\u8a00\u7684 bug\uff0c\u4f46\u548c\u8bed\u8a00\u7684\u5b9e\u73b0\u539f\u7406\u6709\u5173\uff0c js \u6240\u6709\u6570\u5b57\u7edf\u4e00\u4e3a Number, \u5305\u62ec\u6574\u5f62\u5b9e\u9645\u4e0a\u5168\u90fd\u662f\u53cc\u7cbe\u5ea6\uff08double\uff09\u7c7b\u578b\u3002<\/p> \n

\u800cPHP\u4f1a\u533a\u5206 int \u8fd8\u662f float\u3002\u4e0d\u7ba1\u4ec0\u4e48\u8bed\u8a00\uff0c\u53ea\u8981\u6d89\u53ca\u6d6e\u70b9\u8fd0\u7b97\uff0c\u90fd\u662f\u5b58\u5728\u7c7b\u4f3c\u7684\u95ee\u9898\uff0c\u4f7f\u7528\u65f6\u4e00\u5b9a\u8981\u6ce8\u610f\u3002<\/p> \n

\u6d6e\u70b9\u4e8c\u8fdb\u5236\u539f\u7406<\/h3> \n

\u6839\u636e\u56fd\u9645\u6807\u51c6IEEE 754\uff0c\u4efb\u610f\u4e00\u4e2a\u4e8c\u8fdb\u5236\u6d6e\u70b9\u6570V\u53ef\u4ee5\u8868\u793a\u6210\u4e0b\u9762\u7684\u5f62\u5f0f\uff1a<\/p> \n 

V = (-1)s * M * E \n\n    1. (-1)s \u8868\u793a\u7b26\u53f7\u4f4d\uff0c\u5f53s=0\uff0cV\u4e3a\u6b63\u6570\uff1b\u5f53s=1\uff0cV\u4e3a\u8d1f\u6570\u3002\n    2. M\u8868\u793a\u6709\u6548\u6570\u5b57\uff0c\u5927\u4e8e\u7b49\u4e8e1\uff0c\u5c0f\u4e8e2\u3002\n    3. 2E \u8868\u793a\u6307\u6570\u4f4d\u3002<\/code><\/pre> \n 
\u4e3e\u4f8b\u6765\u8bf4\uff1a\u5341\u8fdb\u5236\u7684-5.0\uff0c\u5199\u6210\u4e8c\u8fdb\u5236\u662f-101.0\uff0c\u76f8\u5f53\u4e8e-1.01×22 \u3002\u90a3\u4e48\uff0cs=1\uff0cM=1.01\uff0cE=2\u3002
 IEEE 754\u89c4\u5b9a\uff0c\u5bf9\u4e8e32\u4f4d\u7684\u6d6e\u70b9\u6570\uff0c\u6700\u9ad8\u76841\u4f4d\u662f\u7b26\u53f7\u4f4ds\uff0c\u63a5\u7740\u76848\u4f4d\u662f\u6307\u6570E\uff0c\u5269\u4e0b\u768423\u4f4d\u4e3a\u6709\u6548\u6570\u5b57M\u3002<\/p> \n 
<\/p> \n 
\u5bf9\u4e8e64\u4f4d\u7684\u6d6e\u70b9\u6570\uff0c\u6700\u9ad8\u76841\u4f4d\u662f\u7b26\u53f7\u4f4dS\uff0c\u63a5\u7740\u768411\u4f4d\u662f\u6307\u6570E\uff0c\u5269\u4e0b\u768452\u4f4d\u4e3a\u6709\u6548\u6570\u5b57M\u3002<\/p> \n 
<\/p> \n 
IEEE 754\u5bf9\u6709\u6548\u6570\u5b57M\u548c\u6307\u6570E\uff0c\u8fd8\u6709\u4e00\u4e9b\u7279\u522b\u89c4\u5b9a\u3002<\/p> \n 
\u524d\u9762\u8bf4\u8fc7\uff0c1\u2264M<2\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0cM\u53ef\u4ee5\u5199\u62101.xxxxxx\u7684\u5f62\u5f0f\uff0c\u5176\u4e2dxxxxxx\u8868\u793a\u5c0f\u6570\u90e8\u5206\u3002IEEE 754\u89c4\u5b9a\uff0c\u5728\u8ba1\u7b97\u673a \u5185\u90e8\u4fdd\u5b58M\u65f6\uff0c\u9ed8\u8ba4\u8fd9\u4e2a\u6570\u7684\u7b2c\u4e00\u4f4d\u603b\u662f1\uff0c\u56e0\u6b64\u53ef\u4ee5\u88ab\u820d\u53bb\uff0c\u53ea\u4fdd\u5b58\u540e\u9762\u7684xxxxxx\u90e8\u5206\u3002\u6bd4\u5982\u4fdd\u5b581.01\u7684\u65f6\u5019\uff0c\u53ea \u4fdd\u5b5801\uff0c\u7b49\u5230\u8bfb\u53d6\u7684\u65f6\u5019\uff0c\u518d\u628a\u7b2c\u4e00\u4f4d\u76841\u52a0\u4e0a\u53bb\u3002\u8fd9\u6837\u505a\u7684\u76ee\u7684\uff0c\u662f\u8282\u77011\u4f4d\u6709\u6548\u6570\u5b57\u3002\u4ee532\u4f4d\u6d6e\u70b9\u6570\u4e3a\u4f8b\uff0c\u7559\u7ed9 M\u53ea\u670923\u4f4d\uff0c\u5c06\u7b2c\u4e00\u4f4d\u76841\u820d\u53bb\u4ee5\u540e\uff0c\u7b49\u4e8e\u53ef\u4ee5\u4fdd\u5b5824\u4f4d\u6709\u6548\u6570\u5b57\u3002<\/p> \n 
\u81f3\u4e8e\u6307\u6570E\uff0c\u60c5\u51b5\u5c31\u6bd4\u8f83\u590d\u6742\u3002<\/p> \n 
\u9996\u5148\uff0cE\u4e3a\u4e00\u4e2a\u65e0\u7b26\u53f7\u6574\u6570\uff08unsigned int\uff09\u3002\u8fd9\u610f\u5473\u7740\uff0c\u5982\u679cE\u4e3a8\u4f4d\uff0c\u5b83\u7684\u53d6\u503c\u8303\u56f4\u4e3a0~255\uff1b\u5982\u679cE\u4e3a11\u4f4d\uff0c\u5b83 \u7684\u53d6\u503c\u8303\u56f4\u4e3a0~2047\u3002\u4f46\u662f\uff0c\u6211\u4eec\u77e5\u9053\uff0c\u79d1\u5b66\u8ba1\u6570\u6cd5\u4e2d\u7684E\u662f\u53ef\u4ee5\u51fa\u73b0\u8d1f\u6570\u7684\uff0c\u6240\u4ee5IEEE 754\u89c4\u5b9a\uff0cE\u7684\u771f\u5b9e\u503c\u5fc5\u987b \u7531E\u518d\u51cf\u53bb\u4e00\u4e2a\u4e2d\u95f4\u6570\uff0c\u5bf9\u4e8e8\u4f4d\u7684E\uff0c\u8fd9\u4e2a\u4e2d\u95f4\u6570\u662f127\uff1b\u5bf9\u4e8e11\u4f4d\u7684E\uff0c\u8fd9\u4e2a\u4e2d\u95f4\u6570\u662f1023\u3002
 \u6bd4\u5982\uff0c210 \u7684E\u662f10\uff0c\u6240\u4ee5\u4fdd\u5b58\u621032\u4f4d\u6d6e\u70b9\u6570\u65f6\uff0c\u5fc5\u987b\u4fdd\u5b58\u621010(E\u7684\u771f\u5b9e\u503c)+127=137(E)\uff0c\u537310001001\u3002<\/p> \n 
\u7136\u540e\uff0c\u6307\u6570E\u8fd8\u53ef\u4ee5\u518d\u5206\u6210\u4e09\u79cd\u60c5\u51b5\uff1a
 \uff081\uff09E\u4e0d\u5168\u4e3a0\u6216\u4e0d\u5168\u4e3a1\u3002\u8fd9\u65f6\uff0c\u6d6e\u70b9\u6570\u5c31\u91c7\u7528\u4e0a\u9762\u7684\u89c4\u5219\u8868\u793a\uff0c\u5373\u6307\u6570E\u7684\u8ba1\u7b97\u503c\u51cf\u53bb127\uff08\u62161023\uff09\uff0c\u5f97\u5230\u771f\u5b9e \u503c\uff0c\u518d\u5c06\u6709\u6548\u6570\u5b57M\u524d\u52a0\u4e0a\u7b2c\u4e00\u4f4d\u76841\u3002
 \uff082\uff09E\u5168\u4e3a0\u3002\u8fd9\u65f6\uff0c\u6d6e\u70b9\u6570\u7684\u6307\u6570E\u7b49\u4e8e1-127\uff08\u6216\u80051-1023\uff09\uff0c\u6709\u6548\u6570\u5b57M\u4e0d\u518d\u52a0\u4e0a\u7b2c\u4e00\u4f4d\u76841\uff0c\u800c\u662f\u8fd8\u539f\u4e3a 0.xxxxxx\u7684\u5c0f\u6570\u3002\u8fd9\u6837\u505a\u662f\u4e3a\u4e86\u8868\u793a±0\uff0c\u4ee5\u53ca\u63a5\u8fd1\u4e8e0\u7684\u5f88\u5c0f\u7684\u6570\u5b57\u3002
 \uff083\uff09E\u5168\u4e3a1\u3002\u8fd9\u65f6\uff0c\u5982\u679c\u6709\u6548\u6570\u5b57M\u5168\u4e3a0\uff0c\u8868\u793a±\u65e0\u7a77\u5927\uff08\u6b63\u8d1f\u53d6\u51b3\u4e8e\u7b26\u53f7\u4f4ds\uff09\uff1b\u5982\u679c\u6709\u6548\u6570\u5b57M\u4e0d\u5168\u4e3a0\uff0c\u8868\u793a \u8fd9\u4e2a\u6570\u4e0d\u662f\u4e00\u4e2a\u6570\uff08NaN\uff09\u3002><\/p> \n 
\u53c2\u8003<\/h3> \n 
http:\/\/www.laruence.com\/2013\/03\/26\/2884.html<\/a>
 http:\/\/www.cnblogs.com\/qlwy\/archive\/2012\/08\/17\/2644470.html<\/a><\/p> \n 
\u8f6c\u81ea\uff1ahttp:\/\/www.yinqisen.cn\/blog-782.html<\/a><\/p> \n<\/div>","orderid":"0","title":"\u6709\u5173 PHP \u548c js \u6d6e\u70b9\u8fd0\u7b97\u7684\u5751","smalltitle":"","mid":"0","fname":"PHP","special_id":"0","bak_id":"0","info":"0","hits":"2053","pages":"1","comments":"0","posttime":"2017-10-16 18:19:13","list":"1508149153","username":"admin","author":"","copyfrom":"","copyfromurl":"","titlecolor":"","fonttype":"0","titleicon":"0","picurl":"http:\/\/pic002.cnblogs.com\/images\/2012\/319840\/2012081717465876.png","ispic":"1","yz":"1","yzer":"","yztime":"0","levels":"0","levelstime":"0","keywords":"\u6709\u5173<\/A> PHP<\/A> \u6d6e\u70b9<\/A> \u8fd0\u7b97<\/A>","jumpurl":"","iframeurl":"","style":"","template":"a:3:{s:4:\"head\";s:0:\"\";s:4:\"foot\";s:0:\"\";s:8:\"bencandy\";s:0:\"\";}","target":"0","ip":"113.108.110.181","lastfid":"0","money":"0","buyuser":"","passwd":"","allowdown":"","allowview":"","editer":"","edittime":"0","begintime":"0","endtime":"0","description":"\u6709\u5173 PHP \u548c js \u6d6e\u70b9\u8fd0\u7b97\u7684\u5751","lastview":"1711702267","digg_num":"8128","digg_time":"0","forbidcomment":"0","ifvote":"0","heart":"","htmlname":"","city_id":"0"},"page":"1"}