{"id":1975,"date":"2021-08-03T15:40:22","date_gmt":"2021-08-03T07:40:22","guid":{"rendered":"https:\/\/egonlin.com\/?p=1975"},"modified":"2022-02-07T16:14:43","modified_gmt":"2022-02-07T08:14:43","slug":"%e6%b5%ae%e7%82%b9%e6%95%b0%e7%9a%84%e7%b2%be%e5%ba%a6%e9%97%ae%e9%a2%98","status":"publish","type":"post","link":"https:\/\/egonlin.com\/?p=1975","title":{"rendered":"\u6d6e\u70b9\u6570\u7684\u7cbe\u5ea6\u95ee\u9898"},"content":{"rendered":"

\u6d6e\u70b9\u6570\u7684\u7cbe\u5ea6\u95ee\u9898<\/h1>\n

\u4e00\uff1a\u6d6e\u70b9\u6570\u50a8\u5b58\u7ed3\u6784<\/h2>\n

\u4efb\u4f55\u6570\u636e\u5728\u5185\u5b58\u4e2d\u90fd\u662f\u4ee5\u4e8c\u8fdb\u5236\u7684\u5f62\u5f0f\u5b58\u50a8\u7684\uff0c\u6d6e\u70b9\u6570\u4e5f\u4e0d\u4f8b\u5916\uff0c\u6d6e\u70b9\u6570\u5206\u4e3a\u5355\u7cbe\u5ea6\u4e0e\u53cc\u7cbe\u5ea6<\/p>\n

\u5355\u7cbe\u5ea6\u6d6e\u70b9\u6570float\u53604\u5b57\u8282\u300132\u4f4d<\/p>\n

\u53cc\u7cbe\u5ea6\u6d6e\u70b9\u6570double\u53608\u5b57\u8282\u300164\u4f4d\u3002<\/p>\n

\u9075\u5faaIEEE\u4e8c\u8fdb\u5236\u7b97\u6570\u6807\u51c6\uff1bfloat\u548cdouble\u7684\u4e8c\u8fdb\u5236\u5b58\u50a8\u7ed3\u6784\u90fd\u5206\u6210\u4e09\u90e8\u5206\uff1a\uff1a\u7b26\u53f7\u4f4d+\u6307\u6570\u4f4d+\u5c3e\u6570\u4f4d\u3002<\/p>\n\n\n\n\n\n\n
<\/th>\nSign\/\u7b26\u53f7\u4f4d<\/th>\nExponent\/\u6307\u6570\u4f4d<\/th>\nFraction\/\u5c3e\u6570\u4f4d<\/th>\n<\/tr>\n<\/thead>\n
\u5355\u7cbe\u5ea6<\/td>\n1 [31]<\/td>\n8 [30-23]<\/td>\n23 [22-00]<\/td>\n<\/tr>\n
\u53cc\u7cbe\u5ea6<\/td>\n1 [63]<\/td>\n11 [62-52]<\/td>\n52 [51-00]<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

*\u5355\u7cbe\u5ea6\u6d6e\u70b9\u6570float***<\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/p>\n

\u7b2c\u4e00\u4f4d\u7b26\u53f7\u4f4d\uff0c\u8868\u793a\u8be5\u6570\u7684\u6b63\u8d1f\uff0c0\u8868\u793a\u6b63\u6570\uff0c1\u8868\u793a\u8d1f\u6570<\/p>\n

\u63a5\u4e0b\u67658\u4f4d\u8868\u793a\u8be5\u6d6e\u70b9\u6570\u7684\u6307\u6570\u4f4d<\/p>\n

\u6700\u540e\u768423\u4f4d\u8868\u793a\u5c3e\u6570\u90e8\u5206<\/p>\n

\"\"<\/div><\/p>\n

****<\/strong><\/strong>\u53cc\u7cbe\u5ea6\u6d6e\u70b9\u6570double*****<\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/p>\n

\u7b2c\u4e00\u4f4d\u7b26\u53f7\u4f4d\uff0c\u8868\u793a\u8be5\u6570\u7684\u6b63\u8d1f\uff0c0\u8868\u793a\u6b63\u6570\uff0c1\u8868\u793a\u8d1f\u6570<\/p>\n

\u63a5\u4e0b\u676511\u4f4d\u8868\u793a\u8be5\u6d6e\u70b9\u6570\u7684\u6307\u6570\u4f4d<\/p>\n

\u6700\u540e\u768452\u4f4d\u8868\u793a\u5c3e\u6570\u90e8\u5206<\/p>\n

\"\"<\/div><\/p>\n

\u4e8c\uff1a\u5341\u8fdb\u5236\u6d6e\u70b9\u6570\u5b58\u50a8\u5206\u6790<\/h2>\n

2.1 \u601d\u8def<\/h3>\n

\u200b \u5341\u8fdb\u5236\u6d6e\u70b9\u6570\u82e5\u60f3\u4fdd\u5b58\u5230\u8ba1\u7b97\u673a\u5185\u5b58\u4e2d\uff0c\u5fc5\u987b\u9996\u5148\u8f6c\u6362\u6210\u4e8c\u8fdb\u5236\u6d6e\u70b9\u6570\uff0c\u800c\u4e3a\u4e86\u533a\u5206\u7cbe\u5ea6\uff0c\u6309\u7167IEEE\u6807\u51c6\u9700\u8981\u4ece\u4e8c\u8fdb\u5236\u6d6e\u70b9\u6570\u4e2d\u63d0\u53d6\u4e09\u4e2a\u90e8\u5206\uff1a\u5c3e\u6570\u4f4d\u3001\u6307\u6570\u4f4d\u3001\u7b26\u53f7\u4f4d\uff0c\u8fd9\u4e09\u90e8\u5206\u624d\u662f\u8ba1\u7b97\u673a\u5185\u5b58\u771f\u6b63\u5b58\u50a8\u7684\u4e8c\u8fdb\u5236\u3002<\/p>\n

\u200b \u4ee5\u5355\u7cbe\u5ea6\u4e3a\u4f8b\u6574\u4f53\u6d41\u7a0b\u5982\u4e0b<\/p>\n

\"\"<\/div><\/p>\n

\u200b \u6211\u4eec\u5c31\u4ee5\u5341\u8fdb\u5236\u6d6e\u70b9\u6570173.8125\u5b58\u6210\u5355\u7cbe\u5ea6float32\u4f4d\u4f8b\u5c55\u5f00\u4ecb\u7ecd<\/p>\n

2.2 \u5341\u8fdb\u5236\u6d6e\u70b9\u6570\u8f6c\u6210\u4e8c\u8fdb\u5236\u3001\u79d1\u5b66\u8ba1\u6570\u6cd5<\/h3>\n

\u5341\u8fdb\u5236\u6d6e\u70b9\u6570\u8f6c\u6210\u4e8c\u8fdb\u5236\u65b9\u6cd5<\/strong><\/p>\n

\u2474\u6574\u6570\u90e8\u5206\uff1a\n    1\u3001\u9664\u4ee52\uff0c\u53d6\u51fa\u4f59\u6570\uff0c\u5546\u7ee7\u7eed\u9664\u4ee52\uff0c\u76f4\u5230\u5f97\u52300\u4e3a\u6b62\uff0c\u5c06\u53d6\u51fa\u7684\u4f59\u6570\u9006\u5e8f\n\u2475\u5c0f\u6570\u90e8\u5206\uff1a\n    1\u3001\u4e58\u4ee52\uff0c\u7136\u540e\u53d6\u51fa\u6574\u6570\u90e8\u5206\uff0c\u5c06\u5269\u4e0b\u7684\u5c0f\u6570\u90e8\u5206\u7ee7\u7eed\u4e58\u4ee52\uff0c\u7136\u540e\u518d\u53d6\u6574\u6570\u90e8\u5206\uff0c\u4e00\u76f4\u53d6\u5230\u5c0f\u6570\u90e8\u5206\u4e3a\u96f6\u4e3a\u6b62\u3002\n    2\u3001\u5982\u679c\u6c38\u8fdc\u4e0d\u4e3a\u96f6\uff0c\u5219\u6309\u8981\u6c42\u4fdd\u7559\u8db3\u591f\u4f4d\u6570\u7684\u5c0f\u6570\uff0c\u6700\u540e\u4e00\u4f4d\u505a0\u820d1\u5165\u3002\u5c06\u53d6\u51fa\u7684\u6574\u6570\u987a\u5e8f\u6392\u5217\u3002<\/code><\/pre>\n
\u793a\u4f8b\uff1a25. 625<\/p>\n
\u2474 \u6574\u6570\u90e8\u520625\uff1a\u9664\u4ee52\uff0c\u5546\u7ee7\u7eed\u9664\u4ee52\uff0c\u76f4\u5230\u55460\u4e3a\u6b62\uff0c\u7136\u540e\u5c06\u4f59\u6570\u9006\u5e8f\u6392\u5217\u3002\n25 \/ 2           \u554612 \u4f59 1\n\n12 \/ 2           \u55466  \u4f59 0\n\n6  \/ 2           \u55463  \u4f59 0\n\n3  \/ 2           \u55461  \u4f59 1\n\n1  \/ 2           \u55460\u505c\u6b62  \u4f59 1\n\n\u5f97\u5230\u4f59\u6570\u7ed3\u679c\u9006\u5e8f\u6392\u5e8f\u5f97\u523022\u7684\u4e8c\u8fdb\u5236\u662f: 11001\n\n\u2475 \u5c0f\u6570\u90e8\u52060.625\uff1a\u4e58\u4ee52\uff0c\u53d6\u6574\uff0c\u5c0f\u6570\u90e8\u5206\u7ee7\u7eed\u4e58\u4ee52\uff0c\u53d6\u6574\uff0c\u5f97\u5230\u5c0f\u6570\u90e8\u52060\u4e3a\u6b62\uff0c\u5c06\u6574\u6570\u7ed3\u679c\u987a\u5e8f\u6392\u5217\u3002\n\n0.625*2 = 1.25    \u53d6\u65741    \u5c0f\u6570\u90e8\u5206\u662f0.25\n\n0.25*2  = 0.5     \u53d6\u65740    \u5c0f\u6570\u90e8\u5206\u662f0.5\n\n0.5*2   = 1.0     \u53d6\u65741    \u5c0f\u6570\u90e8\u5206\u662f0\u505c\u6b62\n\n\u5f97\u5230\u6574\u6570\u7ed3\u679c\u987a\u5e8f\u6392\u5e8f\u5f97\u52300.625\u7684\u4e8c\u8fdb\u5236\u662f: 101\n\n\u2476 \u6700\u7ec8\u7ed3\u679c\uff1a\u5341\u8fdb\u5236\uff1a25.625      \uff01\uff01\uff01\u7b49\u4e8e\uff01\uff01\uff01\u4e8c\u8fdb\u5236\uff1a    11001.101 <\/code><\/pre>\n
\u4e8c\u8fdb\u5236\u9700\u8981\u7528\u79d1\u5b66\u8ba1\u6570\u6cd5\u8868\u793a<\/strong><\/p>\n
\u4e8c\u8fdb\u5236\uff1a    11001.101 \n\u79d1\u5b66\u8ba1\u6570\u6cd5\uff1a 11001.101 = 1.1001101*2\uff084\uff09\n\nps\uff1a\u79d1\u5b66\u8ba1\u6570\u6cd5\u4e2d1.1001101\u79f0\u4e4b\u4e3a\u6d6e\u70b9\u6570\u7684\u7cbe\u5ea6<\/code><\/pre>\n
2.3 \u63d0\u53d6\u5c3e\u6570\u4f4d<\/h3>\n
\u200b   \u4ee5\u79d1\u5b66\u8ba1\u6570\u6cd51.1001101*2\uff084\uff09\u4e3a\u51c6\uff0c\u5c3e\u6570\u4f4d\u6307\u7684\u662f\u5c0f\u6570\u70b9\u540e\u7684\u4e8c\u8fdb\u5236\uff0c\u53731.1001101\u4ee3\u8868\u7684\u5c3e\u6570\u662f0.1001101\uff0c\u4e3a\u4ec0\u4e48\u820d\u5f03\u4e86\u5c0f\u6570\u70b9\u5de6\u4fa7\u76841\uff1f\uff1f\uff1f<\/p>\n
\u200b   \u56e0\u4e3a\u5341\u8fdb\u5236\u6d6e\u70b9\u6570\u6362\u7b97\u6210\u4e8c\u8fdb\u5236\u7136\u540e\u8f6c\u5316\u6210\u79d1\u5b66\u8ba1\u6570\u6cd5\u540e\u5c0f\u6570\u70b9\u524d\u9762\u7684\u4e00\u4f4d\u4e00\u5b9a\u662f1\uff08IEEE \u6807\u51c6\u8981\u6c42\u6d6e\u70b9\u6570\u5fc5\u987b\u662f\u89c4\u8303\u7684\u3002\u8fd9\u610f\u5473\u7740\u5c3e\u6570\u7684\u5c0f\u6570\u70b9\u5de6\u4fa7\u5fc5\u987b\u4e3a 1\uff0c\u56e0\u6b64\u6211\u4eec\u5728\u4fdd\u5b58\u5c3e\u6570\u7684\u65f6\u5019\uff0c\u53ef\u4ee5\u7701\u7565\u5c0f\u6570\u70b9\u524d\u9762\u8fd9\u4e2a 1\uff0c\u4ece\u800c\u817e\u51fa\u4e00\u4e2a\u4e8c\u8fdb\u5236\u4f4d\u6765\u4fdd\u5b58\u66f4\u591a\u7684\u5c3e\u6570\uff09\uff0c\u56e0\u6b64\u53ef\u4ee5\u4e0d\u9700\u8981\u5b58\u50a8\u3002<\/p>\n
\u200b   \u6700\u540e\u9488\u5bf9\u5355\u7cbe\u5ea623\u4f4d\u7684\u89c4\u5b9a\uff0c\u5982\u679c\u5c0f\u6570\u70b9\u540e\u7684\u4e8c\u8fdb\u5236\u4f4d\u6570\u4e0d\u591f23\u4f4d\uff0c\u5219\u88650\uff0c\u6240\u4ee5\u6700\u7ec8\u5f97\u5230\u6d6e\u70b9\u6570\u7684\u5c3e\u6570\u4e3a <\/p>\n
1001 1010 0000 0000 0000 000<\/code><\/pre>\n
2.4 \u63d0\u53d6\u6307\u6570\u4f4d<\/h3>\n
\u200b   \u4ee5\u79d1\u5b66\u8ba1\u6570\u6cd51.1001101*2\uff084\uff09\u4e3a\u51c6\uff0c\u6307\u6570\u4f4d\u662f\u5728\u6307\u65704\u7684\u57fa\u7840\u4e0a\u901a\u8fc7\u79fb\u4f4d\u5b58\u50a8\u539f\u7406\u5f97\u5230\u7684<\/p>\n
\u200b   \u79fb\u4f4d\u5b58\u50a8\u539f\u7406\u5982\u4e0b<\/strong><\/p>\n
\u200b   \u7531\u4e8efloat32\u7684\u6307\u6570\u4f4d\u4e3a8\u4f4d\uff0c\u6240\u4ee5\u5982\u679c\u6240\u6709\u4f4d\u90fd\u4e3a0\u7684\u8bdd\uff0c\u53ef\u4ee5\u8868\u793a0\uff0c\u6240\u6709\u4f4d\u90fd\u4e3a1\u7684\u8bdd\uff0c\u53ef\u4ee5\u8868\u793a255\uff0c\u56e0\u6b64\u6307\u6570\u4f4d\u76848\u4f4d0000 0000~1111 1111\u4e0e0~255\u7684\u6570\u503c\u4e00\u4e00\u5bf9\u5e94\uff0c\u53ef\u4ee5\u8fdb\u884c\u8868\u793a\u3002<\/p>\n
\u4f46\u662f\uff01\u6307\u6570\u4e5f\u5206\u6b63\u8d1f\uff0c\u6240\u4ee5\u6b63\u8d1f\u5404\u5360\u4e00\u534a\uff0c\u5373\u6307\u6570\u7684\u8303\u56f4\u73b0\u5728\u53d8\u4e3a-127~128\u3002<\/p>\n
\u56e0\u6b64\u73b0\u5728\u4e5f\u9700\u8981\u4e8c\u8fdb\u52360000 0000~ 1111 1111\u4e0e-127~128\u4e00\u4e00\u5bf9\u5e94\uff08\u6ce8\u610f\uff1a\u6b64\u5904\u7684\u4e8c\u8fdb\u5236\u6570\u53ea\u662f\u4e0e-127~128\u533a\u95f4\u7684\u6570\u5b57\u6709\u5bf9\u5e94\u5173\u7cfb\uff09\uff0c\u5982\u4e0b\u56fe\uff1a<\/p>\n
\"\"<\/div><\/p>\n
\u6240\u4ee5\u672c\u8eab\u8868\u793a0\u7684\u4e8c\u8fdb\u52360000 0000\u73b0\u5728\u9700\u8981\u8868\u793a-127\uff0c\u672c\u8eab\u8868\u793a255\u7684\u4e8c\u8fdb\u52361111 1111\u73b0\u5728\u9700\u8981\u8868\u793a128\uff0c\u8fd9\u5c31\u9020\u6210\u4e86\u4e8c\u8fdb\u5236\u672c\u8eab\u8868\u793a\u7684\u6570\u503c\u6bd4\u73b0\u5728\u9700\u8981\u8868\u793a\u7684\u6570\u503c\u5927\u4e86127\uff08ps\uff1a\u4e5f\u5c31\u662f\u8bf4\u6b64\u5904\u7684\u8fdb\u5236\u662f\u673a\u5668\u6570\uff0c\u800c\u4e0d\u662f\u6211\u4eec\u4eba\u7684\u6570\u5b57\uff0c\u673a\u5668\u6570\u4e0e\u4eba\u7684\u6570\u5b57\u4e4b\u95f4\u5b58\u5728\u7740\u5bf9\u5e94\u5173\u7cfb\u800c\u5df2\uff0c\u673a\u5668\u6570\u7684\u4ef7\u503c\u5728\u4e8e\u7b26\u5408\u8ba1\u7b97\u673a\u7684\u7269\u7406\u8fd0\u7b97\u539f\u7406\uff0c\u6709\u4e86\u5b83\u624d\u80fd\u591f\u8ba9\u8ba1\u7b97\u673a\u4ee5\u81ea\u5df1\u7b80\u5355\u7684\u65b9\u5f0f\u53bb\u8fd0\u7b97\u4eba\u7c7b\u6570\u5b66\u5c42\u9762\u7684\u590d\u6742\u8fd0\u7b97\uff09\uff0c\u6240\u4ee5\u8981\u60f3\u83b7\u5f97\u73b0\u5728\u6307\u6570\u7684\u4e8c\u8fdb\u5236\u8868\u793a\uff0c\u9700\u8981\u5c06\u6307\u6570\u52a0127\u7136\u540e\u8f6c\u6362\u6210\u4e8c\u8fdb\u5236<\/p>\n
\u6d6e\u70b9\u657025.625\u7684\u6307\u6570\u4f4d       4 + 127 = 131          \u7136\u540e\u5c06131\u8f6c\u5316\u6210\u4e8c\u8fdb\u5236               10000011\uff08\u8fd9\u5c31\u662f\u6d6e\u70b9\u6570\u5728\u5e95\u5c42\u5b58\u50a8\u76848\u4f4d\u6307\u6570\u4f4d\uff09<\/p>\n
2.5 \u63d0\u53d6\u7b26\u53f7\u4f4d<\/h3>\n
25.625\u662f\u6b63\u6570\uff0c\u6240\u4ee5\u7b26\u53f7\u4f4d\u4e3a0\u3002<\/p>\n
\u81f3\u6b64\u6211\u4eec\u5f97\u5230\u6d6e\u70b9\u657025.625\u7684\u4e09\u90e8\u5206<\/p>\n
\u7b26\u53f7\u4f4d\uff1a0\n\u6307\u6570\u4f4d\uff1a10000011\n\u5c3e\u6570\u4f4d\uff1a1001 1010 0000 0000 0000 000<\/code><\/pre>\n
\u5408\u5728\u4e00\u8d77\u6d6e\u70b9\u657025.625\u5728\u8ba1\u7b97\u673a\u5e95\u5c42\u5b58\u50a8\u7684\u7ed3\u6784\u4e3a\uff1a 0 10000011 10011010000000000000000<\/p>\n
2.6 \u7ec3\u4e60\u4ee5\u5355\u7cbe\u5ea6\u5b58\u50a8\u6d6e\u70b9\u65700.15625<\/h3>\n
\u5341\u8fdb\u5236\u6d6e\u70b9\u65700.15625\u8f6c\u6210\u4e8c\u8fdb\u5236\u7684\u5f62\u5f0f0.00101\uff0c\u8fc7\u7a0b\u7565<\/p>\n
\u4e8c\u8fdb\u5236\u5f62\u5f0f0.00101\u7684\u79d1\u5b66\u8ba1\u6570\u6cd5\u4e3a\uff1a<\/p>\n
\"\"<\/div><\/p>\n
\u4f9d\u636e\u79d1\u5b66\u8ba1\u6570\u6cd5\u5f97\u5230<\/p>\n
\u5c3e\u6570\uff1a1.01-1 \u5f97 .01\uff0c\u6240\u4ee5\u5c3e\u6570\u4f4d\u662f\uff1a01000000000000000000000\n\u6307\u6570\uff1a-3\uff0c\u79fb\u4f4d\u5b58\u50a8 -3 + 127 \u5f97124\uff0c\u6240\u4ee5\u6307\u6570\u4f4d\u662f\uff1a1111100\n\u7b26\u53f7\uff1a\u6b63\u6570\uff0c\u6240\u4ee5\u7b26\u53f7\u4f4d\uff1a0<\/code><\/pre>\n
\u4e8e\u662f\u5177\u4f53\u7684\u5b58\u653e\u65b9\u6848\u5982\u4e0b<\/p>\n
\"\"<\/div><\/p>\n
2.7 \u601d\u8003\u4ee5\u5355\u7cbe\u5ea6\u5b58\u50a8\u6d6e\u70b9\u65700.1\u7684\u95ee\u9898<\/h3>\n
0.1\u65e0\u6cd5\u7cbe\u786e\u5b58\u50a8\uff0c\u56e0\u4e3a\u5341\u8fdb\u5236\u76840.1\u8f6c\u6362\u6210\u4e8c\u8fdb\u5236\u6c38\u8fdc\u65e0\u6cd5\u5f97\u5230\u4e00\u4e2a\u660e\u786e\u7684\u7ed3\u679c<\/p>\n
\u4e09\uff1a\u6d6e\u70b9\u8fd0\u7b97\u7684\u7cbe\u5ea6\u95ee\u9898<\/h2>\n
\u200b   \u5341\u8fdb\u5236\u6d6e\u70b9\u6570\u8f6c\u6210\u4e8c\u8fdb\u5236\u7136\u540e\u5f97\u5230\u7684\u79d1\u5b66\u8ba1\u6570\u6cd5\u6240\u5305\u542b\u6570\u5b57\u7684\u4e2a\u6570\u79f0\u4e4b\u4e3a\u7cbe\u5ea6
\n\u200b   \u6bd4\u5982\u6211\u4eec\u4e0a\u9762\u5f97\u5230\u76841.1001101\u76f8\u5f53\u4e8e\uff1a\u7cbe\u5ea6\u4e3a8<\/p>\n
\u200b   \u4e0d\u662f\u6240\u6709\u7684\u6d6e\u70b9\u8fd0\u7b97\u90fd\u6709\u7cbe\u5ea6\u95ee\u9898\uff0c\u800c\u6d6e\u70b9\u6570\u5b58\u5728\u7684\u7cbe\u5ea6\u95ee\u9898\u4e3b\u8981\u6765\u81ea\u4e8e\u4e24\u4e2a\u65b9\u9762<\/p>\n
1\u3001\u9996\u5148\u5341\u8fdb\u5236\u7684\u6d6e\u70b9\u6570\u8f6c\u6362\u6210\u4e8c\u8fdb\u5236\u7684\u5c31\u4e0d\u603b\u662f\u7cbe\u786e\u7684\uff0c\u800c\u53ea\u80fd\u662f\u8fd1\u4f3c\u503c\uff0c\u4f8b\u5982\u5341\u8fdb\u5236\u7684\u6d6e\u70b9\u65700.1\n\n2\u3001\u7136\u540e\uff0c\u5373\u4fbf\u5341\u8fdb\u5236\u7684\u6d6e\u70b9\u6570\u8f6c\u6362\u6210\u7684\u4e8c\u8fdb\u5236\u6570\u662f\u7cbe\u786e\u7684\uff0c\u90a3\u4e48\u5728\u5b58\u6210\u5355\u7cbe\u5ea632bits\u6216\u53cc\u7cbe\u5ea664bits\u7684\u8fc7\u7a0b\u4e2d\uff0c\u540c\u6837\u53ef\u80fd\u4f1a\u56e0\u4e3a\u8d85\u51fa\u4e8623bits\u4e0e52bits\u7684\u9650\u5236\u800c\u6ea2\u51fa\uff0c\u540c\u6837\u53ef\u80fd\u4f1a\u51fa\u73b0\u4e0d\u7cbe\u786e<\/code><\/pre>\n
\u200b   \u4e86\u89e3<\/p>\n
    IEEE\u5b9a\u4e49\u4e86\u591a\u79cd\u6d6e\u70b9\u683c\u5f0f\uff0c\u4f46\u6700\u5e38\u89c1\u7684\u662f\u4e09\u79cd\u7c7b\u578b\uff1a\u5355\u7cbe\u5ea6\u3001\u53cc\u7cbe\u5ea6\u3001\u6269\u5c55\u53cc\u7cbe\u5ea6\uff0c\u5206\u522b\u9002\u7528\u4e8e\u4e0d\u540c\u7684\u8ba1\u7b97\u8981\u6c42\u3002\u4e00\u822c\u800c\u8a00\uff0c\u5355\u7cbe\u5ea6\u9002\u5408\u4e00\u822c\u8ba1\u7b97\uff0c\u53cc\u7cbe\u5ea6\u9002\u5408\u79d1\u5b66\u8ba1\u7b97\uff0c\u6269\u5c55\u53cc\u7cbe\u5ea6\u9002\u5408\u9ad8\u7cbe\u5ea6\u8ba1\u7b97\u3002\u4e00\u4e2a\u9075\u5faaIEEE 754\u6807\u51c6\u7684\u7cfb\u7edf\u5fc5\u987b\u652f\u6301\u5355\u7cbe\u5ea6\u7c7b\u578b\uff08\u5f3a\u5236\u7c7b\u578b\uff09\u3001\u6700\u597d\u4e5f\u652f\u6301\u53cc\u7cbe\u5ea6\u7c7b\u578b\uff08\u63a8\u8350\u7c7b\u578b\uff09\uff0c\u81f3\u4e8e\u6269\u5c55\u53cc\u7cbe\u5ea6\u7c7b\u578b\u53ef\u4ee5\u968f\u610f\u3002\u5355\u7cbe\u5ea6\uff08Single Precision\uff09\u6d6e\u70b9\u6570\u662f32\u4f4d\uff08\u53734\u5b57\u8282\uff09\u7684\uff0c\u53cc\u7cbe\u5ea6\uff08Double Precision\uff09\u6d6e\u70b9\u6570\u662f64\u4f4d\uff08\u53738\u5b57\u8282\uff09\u7684\u3002\n\n    Go \u5e73\u53f0\u4e0a\u7684\u6d6e\u70b9\u6570\u7c7b\u578b float \u548c double \u91c7\u7eb3\u4e86 IEEE 754 \u6807\u51c6\u4e2d\u6240\u5b9a\u4e49\u7684\u5355\u7cbe\u5ea6 32 \u4f4d\u6d6e\u70b9\u6570\u548c\u53cc\u7cbe\u5ea6 64 \u4f4d\u6d6e\u70b9\u6570\u7684\u683c\u5f0f\uff0c\u5bf9\u5e94\u7684\u7c7b\u578b\u5206\u522b\u662ffloat32\u4e0efloat64\u3002\n\n\u00a0\u3000\u3000\u6839\u636eIEEE\uff08\u7f8e\u56fd\u7535\u6c14\u548c\u7535\u5b50\u5de5\u7a0b\u5e08\u5b66\u4f1a\uff09754\u6807\u51c6\u8981\u6c42\uff0c\u65e0\u6cd5\u7cbe\u786e\u4fdd\u5b58\u7684\u503c\u5fc5\u987b\u5411\u6700\u63a5\u8fd1\u7684\u53ef\u4fdd\u5b58\u7684\u503c\u8fdb\u884c\u820d\u5165\u3002\u8fd9\u6709\u70b9\u50cf\u6211\u4eec\u719f\u6089\u7684\u5341\u8fdb\u5236\u7684\u56db\u820d\u4e94\u5165\uff0c\u5373\u4e0d\u8db3\u4e00\u534a\u5219\u820d\uff0c\u4e00\u534a\u4ee5\u4e0a\uff08\u5305\u62ec\u4e00\u534a\uff09\u5219\u8fdb\u3002\u4e0d\u8fc7\u5bf9\u4e8e\u4e8c\u8fdb\u5236\u6d6e \u70b9\u6570\u800c\u8a00\uff0c\u8fd8\u591a\u4e00\u6761\u89c4\u77e9\uff0c\u5c31\u662f\u5f53\u9700\u8981\u820d\u5165\u7684\u503c\u521a\u597d\u662f\u4e00\u534a\u65f6\uff0c\u4e0d\u662f\u7b80\u5355\u5730\u8fdb\uff0c\u800c\u662f\u5728\u524d\u540e\u4e24\u4e2a\u7b49\u8ddd\u63a5\u8fd1\u7684\u53ef\u4fdd\u5b58\u7684\u503c\u4e2d\uff0c\u53d6\u5176\u4e2d\u6700\u540e\u4e00\u4f4d\u6709\u6548\u6570\u5b57\u4e3a\u96f6\u8005\u3002\u4ece\u4e0a\u9762 \u7684\u793a\u4f8b\u4e2d\u53ef\u4ee5\u770b\u51fa\uff0c\u5947\u6570\u90fd\u88ab\u820d\u5165\u4e3a\u5076\u6570\uff0c\u4e14\u6709\u820d\u6709\u8fdb\u3002\u6211\u4eec\u53ef\u4ee5\u5c06\u8fd9\u79cd\u820d\u5165\u8bef\u5dee\u7406\u89e3\u4e3a"\u534a\u4f4d"\u7684\u8bef\u5dee\u3002\u6240\u4ee5\uff0c\u4e3a\u4e86\u907f\u514d 7.22 \u4f4d\u5bf9\u5f88\u591a\u4eba\u9020\u6210\u7684\u56f0\u60d1\uff0c\u6709\u4e9b\u6587\u7ae0\u7ecf\u5e38\u4ee5 7.5 \u4f4d\u6765\u8bf4\u660e\u5355\u7cbe\u5ea6\u6d6e\u70b9\u6570\u7684\u7cbe\u5ea6\u95ee\u9898\u3002\n\n    \u63d0\u793a: \u8fd9\u91cc\u91c7\u7528\u7684\u6d6e\u70b9\u6570\u820d\u5165\u89c4\u5219\u6709\u65f6\u88ab\u79f0\u4e3a\u820d\u5165\u5230\u5076\u6570\uff08Round to Even\uff09\u3002\u76f8\u6bd4\u7b80\u5355\u5730\u9022\u4e00\u534a\u5219\u8fdb\u7684\u820d\u5165\u89c4\u5219\uff0c\u820d\u5165\u5230\u5076\u6570\u6709\u52a9\u4e8e\u4ece\u67d0\u4e9b\u89d2\u5ea6\u51cf\u5c0f\u8ba1\u7b97\u4e2d\u4ea7\u751f\u7684\u820d\u5165\u8bef\u5dee\u7d2f\u79ef\u95ee\u9898\u3002\u56e0\u6b64\u4e3a IEEE \u6807\u51c6\u6240\u91c7\u7528\u3002<\/code><\/pre>\n
\u200b   \u5bf9\u4e8e\u5355\u7cbe\u5ea6\u6570\uff0c\u7531\u4e8e\u6211\u4eec\u53ea\u670924\u4f4d\u7684\u5c3e\u6570\uff08\u5176\u4e2d\u4e00\u4f4d\u9690\u85cf,\u53731+23)\uff0c\u6240\u4ee5\u53ef\u4ee5\u8868\u8fbe\u7684\u6700\u5927\u6307\u6570\u4e3a2^24 – 1 = 16,777,215\u3002\u7279\u522b\u7684\uff0c16,777,216 \u662f\u5076\u6570\uff0c\u6240\u4ee5\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u5c06\u5b83\u9664\u4ee5 2 \u5e76\u76f8\u5e94\u5730\u8c03\u6574\u6307\u6570\u6765\u4fdd\u5b58\u8fd9\u4e2a\u6570\uff0c\u8fd9\u683716,777,216 \u540c\u6837\u53ef\u4ee5\u88ab\u7cbe\u786e\u7684\u4fdd\u5b58\u3002\u76f8\u53cd\uff0c\u6570\u503c16,777,217 \u5219\u65e0\u6cd5\u88ab\u7cbe\u786e\u7684\u4fdd\u5b58\u3002\u7531\u6b64\uff0c\u6211\u4eec\u53ef\u4ee5\u770b\u5230\u5355\u7cbe\u5ea6\u7684\u6d6e\u70b9\u6570\u53ef\u4ee5\u8868\u8fbe\u7684\u5341\u8fdb\u5236\u6570\u503c\u4e2d\uff0c\u771f\u6b63\u6709\u6548\u7684\u6570\u5b57\u4e0d\u9ad8\u4e8e 8 \u4f4d\u3002<\/p>\n
\u3000\u3000\u4e8b\u5b9e\u4e0a\uff0c\u5bf9\u76f8\u5bf9\u8bef\u5dee\u7684\u6570\u503c\u5206\u6790\u7ed3\u679c\u663e\u793a\u6709\u6548\u7684\u7cbe\u5ea6\u5927\u7ea6\u4e3a 7.22 \u4f4d\u3002<\/p>\n
\"\"<\/div><\/p>\n
\u200b   \u6240\u4ee5\u5728go\u4e2d\u5173\u4e8e\u4e0b\u8ff0\u6d6e\u70b9\u8fd0\u7b97\u7684\u8bef\u5dee\uff0c\u4f60\u4fbf\u53ef\u4ee5\u7406\u89e3\u4e86<\/p>\n
\u200b   \u4f8b1\uff1a\u56e0\u4e3a\u6ea2\u51fa\u800c\u5bfc\u81f4\u7cbe\u5ea6\u95ee\u9898<\/p>\n
var f float32 = 16777216 \/\/ 1 << 24\nfmt.Println(f == f+1)    \/\/ "true"!\uff0c\u56e0\u4e3af+1\u7684\u7ed3\u679c\u6ea2\u51fa\u4e86\uff0c\u6240\u4ee5f+1\u5f97\u5230\u7684\u8fd8\u662f16777216<\/code><\/pre>\n
\u200b   \u4f8b2\uff1a\u56e0\u4e3a\u8fd1\u4f3c\u503c\u800c\u5bfc\u81f4\u7cbe\u5ea6\u95ee\u9898<\/p>\n
var x=0.1 \/\/ \u5341\u8fdb\u503c\u7684\u6d6e\u70b9\u6570\u5728\u8f6c\u6210\u4e8c\u8fdb\u5236\u65f6\u62ff\u5230\u7684\u5c31\u662f\u4e00\u4e2a\u8fd1\u4f3c\u503c\uff0c\u5b58\u53d8\u91cfx\u7684\u65f6\u5019\u5c31\u51fa\u73b0\u4e86\u7cbe\u5ea6\u95ee\u9898\nvar y=0.2\nvar z= x+y \/\/ \u53d6\u51fa\u53d8\u91cfx\u5728\u5185\u5b58\u4e2d\u7684\u975e\u7cbe\u786e\u503c\u8fdb\u884c\u8fd0\u7b97\uff0c\u5fc5\u7136\u7ed3\u679c\u6709\u7cbe\u5ea6\u95ee\u9898\nfmt.Println(z) \/\/ 0.30000000000000004\n\nfmt.Println(z == 0.3)  \/\/ "false"!\n\n\/\/ \u6ce8\u610f\uff1a\u6b64\u5904\u62ff\u5230\u7684\u4e0d\u662f\u4e0a\u9762\u90a3\u4e2a\u4e0d\u7cbe\u786e\u7684x\uff0c\u800c\u662f\u4e00\u4e2a\u5b9e\u5b9e\u5728\u5728\u76840.1\uff0c\u6240\u4ee5\u7ed3\u679c\u4e3atrue\nfmt.Println(0.1+0.2==0.3) \/\/ true<\/code><\/pre>\n
\u200b   \u89e3\u51b3\u7cbe\u5ea6\u95ee\u9898\uff0c\u7528decimal\uff0c\u5e95\u5c42\u5bf9\u6d6e\u70b9\u6570\u7684\u5904\u7406\u7528\u7684\u662f\u5b57\u7b26\u4e32<\/p>\n
package main\n\nimport (\n    "fmt"\n    "github.com\/shopspring\/decimal"\n)\n\nfunc main() {\n    \/\/ =================\u7cbe\u5ea6\u95ee\u9898==================\n    \/\/var a float64=1.5\n    \/\/var b float64=1.3\n    \/\/var result float64=a-b\n    \/\/\n    \/\/fmt.Printf("%.20f\\n ",result) \/\/ 0.19999999999999995559\n    \/\/fmt.Println(result == 0.2) \/\/ false\n    \/\/\n    \/\/\n    \/\/var c float64 = 78.6\n    \/\/fmt.Println(int64(c *100)) \/\/\u6d6e\u70b9\u6570\u8fd0\u7b97\u540e\uff0c\u8f6c\u6362\u6210int64\u4f4d\n\n    \/\/ =================\u89e3\u51b3\u65b9\u6848==================\n    num1:=decimal.NewFromFloat(1.5)\n    num2:=decimal.NewFromFloat(1.2)\n    num3:=decimal.NewFromFloat(0.3)\n    \/\/\n    res1:=num1.Sub(num2)\n    fmt.Println(res1.Cmp(num3)) \/\/ \u8fd4\u56de0\u4ee3\u8868\u6210\u7acb\n    \/\/\n    num4:=decimal.NewFromFloat(78.6)\n    num5:=decimal.NewFromFloat(100)\n    res2:=num4.Mul(num5) \/\/num4*num5\n    fmt.Println("\u7ed3\u679c\u662f:",res2.String())\n\n}<\/code><\/pre>\n
\u200b   ps\uff1a\u5b57\u7b26\u4e32\u4e5f\u53ef\u4ee5\u8f6c\u6210decimal,<\/p>\n
package main\n\nimport (\n    "log"\n    "github.com\/shopspring\/decimal"\n)\n\nfunc main() {\n    xdecimal, err := decimal.NewFromString("1129.6")\n    if err != nil {\n        log.Println("\u8f6c\u5316decimal\u5931\u8d25", err)\n    }\n    ydecimal  := decimal.NewFromFloat(3)\n\n    resultdecimal := xdecimal.Mul(ydecimal)\n    log.Println(resultdecimal)  \/\/112960\n\n}\n<\/code><\/pre>\n
\u200b   \u5982\u679c\u5bf9\u7cbe\u5ea6\u7684\u8981\u6c42\u53ea\u662f\u4fdd\u7559\u5230\u5c0f\u6570\u70b9\u540e\u51e0\u4f4d\uff0c\u6211\u4eec\u4e5f\u53ef\u4ee5\u81ea\u5b9a\u4e49\u51fd\u6570\u6765\u5b9e\u73b0<\/p>\n
package main\n\nimport (\n    "fmt"\n    "strconv"\n)\n\n\/\/ \u622a\u53d6\u5c0f\u6570\u4f4d\u6570\nfunc Decimal(f float64, n int) float64 {\n    \/\/ strconv.Itoa()\u51fd\u6570\u7684\u53c2\u6570\u662f\u4e00\u4e2a\u6574\u578b\u6570\u5b57\uff0c\u5b83\u53ef\u4ee5\u5c06\u6570\u5b57\u8f6c\u6362\u6210\u5bf9\u5e94\u7684\u5b57\u7b26\u4e32\u7c7b\u578b\u7684\u6570\u5b57\n    format := "%." + strconv.Itoa(n) + "f"\n    res, _ := strconv.ParseFloat(fmt.Sprintf(format, f), 64)\n    return res\n}\n\nfunc main() {\n    var x = 0.1\n    var y = 0.2\n\n    var z = x + y\n    fmt.Println(z == 0.3)       \/\/ false\n    fmt.Println(0.1+0.2 == 0.3) \/\/ true\n\n    z = Decimal(z, 1)\n    fmt.Println(z == 0.3) \/\/ true\n\n}<\/code><\/pre>\n
\u6269\u5c55\u9605\u8bfb\uff1a<\/p>\n
https:\/\/blog.csdn.net\/u010379324\/article\/details\/90581631#_136<\/a><\/p>\n
https:\/\/blog.csdn.net\/big_data1\/article\/details\/82356206<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
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