{"id":1062745,"date":"2024-12-31T15:54:35","date_gmt":"2024-12-31T07:54:35","guid":{"rendered":"https:\/\/docs.pingcode.com\/ask\/ask-ask\/1062745.html"},"modified":"2024-12-31T15:54:37","modified_gmt":"2024-12-31T07:54:37","slug":"python%e4%b8%ad%e6%b5%ae%e7%82%b9%e6%95%b0%e5%8a%a0%e5%87%8f%e5%a6%82%e4%bd%95%e8%a1%a8%e7%a4%ba","status":"publish","type":"post","link":"https:\/\/docs.pingcode.com\/ask\/ask-ask\/1062745.html","title":{"rendered":"python\u4e2d\u6d6e\u70b9\u6570\u52a0\u51cf\u5982\u4f55\u8868\u793a"},"content":{"rendered":"

\"python\u4e2d\u6d6e\u70b9\u6570\u52a0\u51cf\u5982\u4f55\u8868\u793a\"<\/p>\n

Python \u4e2d\u7684\u6d6e\u70b9\u6570\u52a0\u51cf\u64cd\u4f5c\u53ef\u4ee5\u901a\u8fc7\u4f7f\u7528\u6807\u51c6\u7684\u7b97\u672f\u8fd0\u7b97\u7b26\u6765\u5b9e\u73b0\uff1a+<\/code> \u7528\u4e8e\u52a0\u6cd5\uff0c-<\/code> \u7528\u4e8e\u51cf\u6cd5\u3002<\/strong> \u4f8b\u5982\uff0ca + b<\/code> \u8868\u793a\u4e24\u4e2a\u6d6e\u70b9\u6570 a<\/code> \u548c b<\/code> \u7684\u52a0\u6cd5\u8fd0\u7b97\uff0ca - b<\/code> \u8868\u793a\u4e24\u4e2a\u6d6e\u70b9\u6570 a<\/code> \u548c b<\/code> \u7684\u51cf\u6cd5\u8fd0\u7b97\u3002Python \u7684\u6d6e\u70b9\u6570\u8868\u793a\u65b9\u5f0f\u57fa\u4e8e IEEE 754 \u6807\u51c6\uff0c\u8fd9\u662f\u4e00\u79cd\u7528\u4e8e\u6d6e\u70b9\u6570\u8fd0\u7b97\u7684\u56fd\u9645\u6807\u51c6\u3002<\/p>\n<\/p>\n

\u5176\u4e2d\u4e00\u70b9\u9700\u8981\u8be6\u7ec6\u63cf\u8ff0\u7684\u662f \u6d6e\u70b9\u6570\u7cbe\u5ea6\u95ee\u9898<\/strong>\u3002\u6d6e\u70b9\u6570\u5728\u8ba1\u7b97\u673a\u4e2d\u65e0\u6cd5\u7cbe\u786e\u8868\u793a\u5927\u591a\u6570\u7684\u5b9e\u6570\uff0c\u5c24\u5176\u662f\u5c0f\u6570\u90e8\u5206\u3002\u7531\u4e8e\u6d6e\u70b9\u6570\u662f\u901a\u8fc7\u4e8c\u8fdb\u5236\u6765\u8868\u793a\u7684\uff0c\u8fd9\u5bfc\u81f4\u4e86\u67d0\u4e9b\u5341\u8fdb\u5236\u7684\u5c0f\u6570\u65e0\u6cd5\u7cbe\u786e\u8868\u793a\uff0c\u4ece\u800c\u4ea7\u751f\u4e86\u7cbe\u5ea6\u8bef\u5dee\u3002\u8fd9\u4e2a\u7cbe\u5ea6\u8bef\u5dee\u5728\u8fdb\u884c\u5927\u91cf\u8ba1\u7b97\u65f6\u53ef\u80fd\u4f1a\u7d2f\u79ef\uff0c\u4ece\u800c\u5f71\u54cd\u6700\u7ec8\u7ed3\u679c\u7684\u7cbe\u786e\u6027\u3002\u4e3a\u4e86\u5904\u7406\u8fd9\u79cd\u60c5\u51b5\uff0c\u53ef\u4ee5\u91c7\u7528\u4e00\u4e9b\u65b9\u6cd5\u6765\u51cf\u5c0f\u8bef\u5dee\u7684\u5f71\u54cd\uff0c\u5982\u4f7f\u7528 decimal<\/code> \u6a21\u5757\u8fdb\u884c\u9ad8\u7cbe\u5ea6\u8ba1\u7b97\uff0c\u6216\u8005\u901a\u8fc7\u820d\u5165\u51fd\u6570\u8fdb\u884c\u9002\u5f53\u7684\u820d\u5165\u5904\u7406\u3002<\/p>\n<\/p>\n

\u4e00\u3001\u6d6e\u70b9\u6570\u7684\u57fa\u672c\u8868\u793a<\/strong><\/h2>\n

\u5728 Python \u4e2d\uff0c\u6d6e\u70b9\u6570\u53ef\u4ee5\u901a\u8fc7\u76f4\u63a5\u8d4b\u503c\u6765\u8868\u793a\u3002\u4f8b\u5982\uff1a<\/p>\n<\/p>\n

a = 3.14<\/p>\n
b = 2.71<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u8fd9\u91cc\uff0ca<\/code> \u548c b<\/code> \u90fd\u662f\u6d6e\u70b9\u6570\u3002\u6d6e\u70b9\u6570\u7684\u52a0\u51cf\u6cd5\u53ef\u4ee5\u76f4\u63a5\u4f7f\u7528\u7b97\u672f\u8fd0\u7b97\u7b26 +<\/code> \u548c -<\/code> \u6765\u5b9e\u73b0\uff1a<\/p>\n<\/p>\n
c = a + b<\/p>\n
d = a - b<\/p>\n
print("a + b =", c)<\/p>\n
print("a - b =", d)<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u4e8c\u3001\u6d6e\u70b9\u6570\u7684\u7cbe\u5ea6<\/strong><\/h2>\n
\u7531\u4e8e\u6d6e\u70b9\u6570\u5728\u8ba1\u7b97\u673a\u4e2d\u7684\u8868\u793a\u65b9\u5f0f\u6709\u9650\uff0c\u4f1a\u5e26\u6765\u4e00\u4e9b\u7cbe\u5ea6\u95ee\u9898\u3002\u4f8b\u5982\uff1a<\/p>\n<\/p>\n
a = 0.1<\/p>\n
b = 0.2<\/p>\n
print(a + b)  # \u8f93\u51fa 0.30000000000000004 \u800c\u4e0d\u662f 0.3<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u8fd9\u662f\u56e0\u4e3a 0.1 \u548c 0.2 \u5728\u4e8c\u8fdb\u5236\u4e2d\u65e0\u6cd5\u7cbe\u786e\u8868\u793a\uff0c\u5bfc\u81f4\u4e86\u52a0\u6cd5\u8fd0\u7b97\u7684\u7ed3\u679c\u51fa\u73b0\u4e86\u5fae\u5c0f\u7684\u8bef\u5dee\u3002\u4e3a\u4e86\u89e3\u51b3\u8fd9\u4e00\u95ee\u9898\uff0c\u53ef\u4ee5\u4f7f\u7528 decimal<\/code> \u6a21\u5757\u3002<\/p>\n<\/p>\n
\u4e09\u3001\u4f7f\u7528 decimal \u6a21\u5757\u63d0\u9ad8\u7cbe\u5ea6<\/strong><\/h2>\n
decimal<\/code> \u6a21\u5757\u63d0\u4f9b\u4e86\u9ad8\u7cbe\u5ea6\u7684\u6d6e\u70b9\u6570\u8fd0\u7b97\uff0c\u53ef\u4ee5\u7528\u6765\u907f\u514d\u7cbe\u5ea6\u8bef\u5dee\u3002\u4f8b\u5982\uff1a<\/p>\n<\/p>\n
from decimal import Decimal<\/p>\n
a = Decimal('0.1')<\/p>\n
b = Decimal('0.2')<\/p>\n
print(a + b)  # \u8f93\u51fa 0.3<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u8fd9\u91cc\uff0cDecimal<\/code> \u7c7b\u53ef\u4ee5\u7cbe\u786e\u8868\u793a\u5c0f\u6570\uff0c\u907f\u514d\u4e86\u6d6e\u70b9\u6570\u7684\u7cbe\u5ea6\u95ee\u9898\u3002<\/p>\n<\/p>\n
\u56db\u3001\u820d\u5165\u5904\u7406<\/strong><\/h2>\n
\u4e3a\u4e86\u51cf\u5c11\u6d6e\u70b9\u6570\u8fd0\u7b97\u4e2d\u7684\u8bef\u5dee\uff0c\u53ef\u4ee5\u4f7f\u7528 Python \u63d0\u4f9b\u7684\u820d\u5165\u51fd\u6570\u3002\u4f8b\u5982\uff0cround()<\/code> \u51fd\u6570\u53ef\u4ee5\u7528\u6765\u5bf9\u6d6e\u70b9\u6570\u8fdb\u884c\u820d\u5165\uff1a<\/p>\n<\/p>\n
a = 0.1<\/p>\n
b = 0.2<\/p>\n
c = a + b<\/p>\n
print(round(c, 2))  # \u8f93\u51fa 0.3<\/p>\n
<\/code><\/pre>\n<\/p>\n
round()<\/code> \u51fd\u6570\u5c06\u6d6e\u70b9\u6570 c<\/code> \u820d\u5165\u5230\u5c0f\u6570\u70b9\u540e 2 \u4f4d\uff0c\u4ece\u800c\u51cf\u5c11\u4e86\u7cbe\u5ea6\u8bef\u5dee\u3002<\/p>\n<\/p>\n
\u4e94\u3001\u79d1\u5b66\u8ba1\u7b97\u4e2d\u7684\u6d6e\u70b9\u6570<\/strong><\/h2>\n
\u5728\u79d1\u5b66\u8ba1\u7b97\u4e2d\uff0c\u6d6e\u70b9\u6570\u8fd0\u7b97\u7684\u7cbe\u5ea6\u95ee\u9898\u5c24\u4e3a\u91cd\u8981\u3002\u4e3a\u4e86\u786e\u4fdd\u8ba1\u7b97\u7ed3\u679c\u7684\u51c6\u786e\u6027\uff0c\u53ef\u4ee5\u4f7f\u7528 numpy<\/code> \u6a21\u5757\u4e2d\u7684 float64<\/code> \u7c7b\u578b\uff0c\u8be5\u7c7b\u578b\u63d0\u4f9b\u4e86\u53cc\u7cbe\u5ea6\u6d6e\u70b9\u6570\u8fd0\u7b97\uff1a<\/p>\n<\/p>\n
import numpy as np<\/p>\n
a = np.float64(0.1)<\/p>\n
b = np.float64(0.2)<\/p>\n
print(a + b)  # \u8f93\u51fa 0.3<\/p>\n
<\/code><\/pre>\n<\/p>\n
float64<\/code> \u7c7b\u578b\u63d0\u4f9b\u4e86\u66f4\u9ad8\u7684\u7cbe\u5ea6\uff0c\u53ef\u4ee5\u6709\u6548\u51cf\u5c11\u6d6e\u70b9\u6570\u8fd0\u7b97\u4e2d\u7684\u8bef\u5dee\u3002<\/p>\n<\/p>\n
\u516d\u3001\u6d6e\u70b9\u6570\u6bd4\u8f83<\/strong><\/h2>\n
\u7531\u4e8e\u6d6e\u70b9\u6570\u7684\u7cbe\u5ea6\u95ee\u9898\uff0c\u76f4\u63a5\u6bd4\u8f83\u4e24\u4e2a\u6d6e\u70b9\u6570\u53ef\u80fd\u4f1a\u5bfc\u81f4\u610f\u5916\u7684\u7ed3\u679c\u3002\u4f8b\u5982\uff1a<\/p>\n<\/p>\n
a = 0.1 + 0.2<\/p>\n
b = 0.3<\/p>\n
print(a == b)  # \u8f93\u51fa False<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u8fd9\u662f\u56e0\u4e3a a<\/code> \u548c b<\/code> \u5728\u4e8c\u8fdb\u5236\u4e2d\u5e76\u4e0d\u5b8c\u5168\u76f8\u7b49\u3002\u4e3a\u4e86\u8fdb\u884c\u6d6e\u70b9\u6570\u6bd4\u8f83\uff0c\u53ef\u4ee5\u4f7f\u7528\u4e00\u4e2a\u5c0f\u7684\u9608\u503c\uff08\u5982 epsilon<\/code>\uff09\u6765\u5224\u65ad\u4e24\u4e2a\u6d6e\u70b9\u6570\u662f\u5426\u8db3\u591f\u63a5\u8fd1\uff1a<\/p>\n<\/p>\n
epsilon = 1e-10<\/p>\n
a = 0.1 + 0.2<\/p>\n
b = 0.3<\/p>\n
print(abs(a - b) < epsilon)  # \u8f93\u51fa True<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u8fd9\u79cd\u65b9\u6cd5\u53ef\u4ee5\u6709\u6548\u907f\u514d\u6d6e\u70b9\u6570\u6bd4\u8f83\u4e2d\u7684\u8bef\u5dee\u3002<\/p>\n<\/p>\n
\u4e03\u3001\u6d6e\u70b9\u6570\u7684\u8f6c\u6362<\/strong><\/h2>\n
\u5728 Python \u4e2d\uff0c\u53ef\u4ee5\u5c06\u6574\u6570\u548c\u5b57\u7b26\u4e32\u8f6c\u6362\u4e3a\u6d6e\u70b9\u6570\u3002\u4f8b\u5982\uff1a<\/p>\n<\/p>\n
a = float(1)<\/p>\n
b = float('3.14')<\/p>\n
print(a, b)  # \u8f93\u51fa 1.0 3.14<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u8fd9\u79cd\u8f6c\u6362\u64cd\u4f5c\u975e\u5e38\u65b9\u4fbf\uff0c\u53ef\u4ee5\u5728\u9700\u8981\u8fdb\u884c\u6d6e\u70b9\u6570\u8fd0\u7b97\u65f6\u4f7f\u7528\u3002<\/p>\n<\/p>\n
\u516b\u3001\u603b\u7ed3<\/strong><\/h2>\n
\u6d6e\u70b9\u6570\u5728 Python \u4e2d\u7684\u8868\u793a\u548c\u8fd0\u7b97\u975e\u5e38\u7b80\u5355\uff0c\u4f46\u9700\u8981\u6ce8\u610f\u5176\u7cbe\u5ea6\u95ee\u9898\u3002\u4e3a\u4e86\u63d0\u9ad8\u8ba1\u7b97\u7684\u51c6\u786e\u6027\uff0c\u53ef\u4ee5\u4f7f\u7528 decimal<\/code> \u6a21\u5757\u548c numpy<\/code> \u6a21\u5757\u63d0\u4f9b\u7684\u9ad8\u7cbe\u5ea6\u6d6e\u70b9\u6570\u7c7b\u578b\u3002\u6b64\u5916\uff0c\u901a\u8fc7\u9002\u5f53\u7684\u820d\u5165\u5904\u7406\u548c\u6d6e\u70b9\u6570\u6bd4\u8f83\u65b9\u6cd5\uff0c\u53ef\u4ee5\u6709\u6548\u51cf\u5c11\u6d6e\u70b9\u6570\u8fd0\u7b97\u4e2d\u7684\u8bef\u5dee\u3002\u4e86\u89e3\u8fd9\u4e9b\u6280\u5de7\u548c\u65b9\u6cd5\uff0c\u53ef\u4ee5\u5e2e\u52a9\u6211\u4eec\u5728\u5b9e\u9645\u7f16\u7a0b\u4e2d\u66f4\u597d\u5730\u5904\u7406\u6d6e\u70b9\u6570\u8fd0\u7b97\u3002<\/p>\n<\/p>\n
\u76f8\u5173\u95ee\u7b54FAQs\uff1a<\/strong><\/h2>\n
 \u5728Python\u4e2d\uff0c\u5982\u4f55\u7cbe\u786e\u8868\u793a\u6d6e\u70b9\u6570\u7684\u52a0\u51cf\u6cd5\uff1f<\/strong>
\u5728Python\u4e2d\uff0c\u6d6e\u70b9\u6570\u7684\u52a0\u51cf\u6cd5\u53ef\u4ee5\u901a\u8fc7\u5185\u7f6e\u7684\u8fd0\u7b97\u7b26\u8fdb\u884c\uff0c\u4f8b\u5982\u4f7f\u7528+<\/code>\u548c-<\/code>\u6765\u8fdb\u884c\u52a0\u6cd5\u548c\u51cf\u6cd5\u8fd0\u7b97\u3002\u7136\u800c\uff0c\u7531\u4e8e\u6d6e\u70b9\u6570\u5728\u8ba1\u7b97\u673a\u5185\u90e8\u7684\u8868\u793a\u5b58\u5728\u7cbe\u5ea6\u95ee\u9898\uff0c\u6709\u65f6\u4f1a\u5bfc\u81f4\u8fd0\u7b97\u7ed3\u679c\u51fa\u73b0\u5c0f\u7684\u8bef\u5dee\u3002\u4e3a\u4e86\u63d0\u9ad8\u7cbe\u786e\u5ea6\uff0c\u5efa\u8bae\u4f7f\u7528decimal<\/code>\u6a21\u5757\uff0c\u8be5\u6a21\u5757\u63d0\u4f9b\u4e86\u5bf9\u6d6e\u70b9\u6570\u8fdb\u884c\u9ad8\u7cbe\u5ea6\u8fd0\u7b97\u7684\u80fd\u529b\u3002<\/p>\n
\u4f7f\u7528decimal\u6a21\u5757\u8fdb\u884c\u6d6e\u70b9\u6570\u8fd0\u7b97\u6709\u4ec0\u4e48\u4f18\u52bf\uff1f<\/strong>
\u4f7f\u7528decimal<\/code>\u6a21\u5757\u53ef\u4ee5\u907f\u514d\u6d6e\u70b9\u6570\u8fd0\u7b97\u4e2d\u7684\u7cbe\u5ea6\u635f\u5931\u3002\u8be5\u6a21\u5757\u5141\u8bb8\u7528\u6237\u8bbe\u7f6e\u7cbe\u5ea6\u7ea7\u522b\uff0c\u5e76\u63d0\u4f9b\u4e86\u4e30\u5bcc\u7684\u6570\u503c\u64cd\u4f5c\u548c\u683c\u5f0f\u5316\u9009\u9879\u3002\u901a\u8fc7\u4f7f\u7528Decimal<\/code>\u7c7b\uff0c\u4f60\u53ef\u4ee5\u8fdb\u884c\u52a0\u51cf\u6cd5\u8fd0\u7b97\u800c\u4e0d\u4f1a\u906d\u9047\u5e38\u89c1\u7684\u6d6e\u70b9\u6570\u8bef\u5dee\u3002\u4f8b\u5982\uff0cfrom decimal import Decimal<\/code>\u5bfc\u5165\u540e\uff0c\u53ef\u4ee5\u4f7f\u7528Decimal('0.1') + Decimal('0.2')<\/code>\u5f97\u5230\u51c6\u786e\u7684\u7ed3\u679cDecimal('0.3')<\/code>\u3002<\/p>\n
\u5728Python\u4e2d\u5982\u4f55\u5904\u7406\u6d6e\u70b9\u6570\u52a0\u51cf\u6cd5\u7684\u820d\u5165\u95ee\u9898\uff1f<\/strong>
\u5728\u8fdb\u884c\u6d6e\u70b9\u6570\u52a0\u51cf\u6cd5\u65f6\uff0c\u820d\u5165\u95ee\u9898\u662f\u4e00\u4e2a\u5e38\u89c1\u7684\u6311\u6218\u3002\u4f7f\u7528decimal<\/code>\u6a21\u5757\u53ef\u4ee5\u6709\u6548\u7ba1\u7406\u820d\u5165\u65b9\u5f0f\uff0c\u7528\u6237\u53ef\u4ee5\u9009\u62e9\u4e0d\u540c\u7684\u820d\u5165\u7b56\u7565\uff0c\u5982ROUND_HALF_UP<\/code>\u3001ROUND_DOWN<\/code>\u7b49\u3002\u6b64\u5916\uff0cround()<\/code>\u51fd\u6570\u4e5f\u53ef\u4ee5\u7528\u4e8e\u63a7\u5236\u7ed3\u679c\u7684\u5c0f\u6570\u4f4d\u6570\u3002\u7406\u89e3\u5e76\u5e94\u7528\u5408\u9002\u7684\u820d\u5165\u65b9\u6cd5\uff0c\u53ef\u4ee5\u786e\u4fdd\u5728\u8d22\u52a1\u8ba1\u7b97\u7b49\u5bf9\u7cbe\u5ea6\u8981\u6c42\u8f83\u9ad8\u7684\u573a\u666f\u4e2d\u5f97\u5230\u7406\u60f3\u7684\u7ed3\u679c\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"Python \u4e2d\u7684\u6d6e\u70b9\u6570\u52a0\u51cf\u64cd\u4f5c\u53ef\u4ee5\u901a\u8fc7\u4f7f\u7528\u6807\u51c6\u7684\u7b97\u672f\u8fd0\u7b97\u7b26\u6765\u5b9e\u73b0\uff1a+ \u7528\u4e8e\u52a0\u6cd5\uff0c- \u7528\u4e8e\u51cf\u6cd5\u3002 \u4f8b\u5982\uff0ca + […]","protected":false},"author":3,"featured_media":1062750,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[37],"tags":[],"acf":[],"_links":{"self":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/1062745"}],"collection":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/comments?post=1062745"}],"version-history":[{"count":"1","href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/1062745\/revisions"}],"predecessor-version":[{"id":1062751,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/1062745\/revisions\/1062751"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media\/1062750"}],"wp:attachment":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media?parent=1062745"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/categories?post=1062745"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/tags?post=1062745"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}