编程代码网1.在python中 float是什么意思?
float是一种数据类型。
浮点型数据类型，FLOAT 数据类型用于存储单精度浮点数或双精度浮点数。浮点数使用 IEEE（电气和电子工程师协会）格式。浮点类型的单精度值具有 4 个字节，包括一个符号位、一个 8 位 二进制指数和一个 23 位尾数。
由于尾数的高顺序位始终为 1，因此它不是以数字形式存储的。此表示形式为 float 类型提供了一个大约在 -3.4E+38 ~ 3.4E+38 之间的范围。
扩展资料：
相关用法
存储为二进制分数的尾数大于或等于 1 且小于 2。对于 float 和 double 类型，最高有效位位置的尾数中有一个隐含的前导 1，这样，尾数实际上分别为 24 和 53 位长，即使最高有效位从未存储在内存中也是如此。
浮点包可以将二进制浮点数存储为非标准化数，而不使用刚刚介绍的存储方法。“非标准化数”是带有保留指数值的非零浮点数，其中尾数的最高有效位为 0。
通过使用非标准化格式，浮点数的范围可以扩展，但会失去精度。您无法控制浮点数以标准化形式还是非标准化形式表示；浮点包决定了表示形式。
用法举例
如果存储比精度更重要，请考虑对浮点变量使用 float 类型。相反，如果精度是最重要的条件，则使用 double 类型。
浮点变量可以提升为更大基数的类型（从 float 类型到 double 类型）。当您对浮点变量执行算术时，通常会出现提升。此算术始终以与具有最高精度的变量一样高的精度执行。例如，请考虑下列类型声明：
float f_short;double f_long;long double f_longer;f_short = f_short * f_long;
在前面的示例中，变量f_short提升到类型 double 并且与f_long相乘；然后，结果舍入到类型 float，然后赋给f_short。
参考资料来源：百度百科-FLOAT
2.refer to 用法
一、refer。
to。的用法 1.表示“把……提交给……”或“把……委托给……”之意.例如： Tom is going to refer the matter to the meeting.汤姆打算把这件事提交到会议上去处理. I don't want to refer this patient to an irresponsible doctor.我不想把这个病人交给一个不负责的医生. 2.表示“使……向……请教”或“使……求助于……”之意.例如： I referred her to Tom for further information.我让她到汤姆那儿去询问详情. The teacher referred me to Chapter III.老师叫我去查第三章. 3.表示“把……归功于……”之意.例如： He referred his success to the good education he had had.他把他的成功归功于他所受的良好教育. 4.表示“认为……起源于……”之意.例如： The invention of the papermaking is referred to China.造纸术起源于中国. 二、refer to 的用法 1.表示“查阅”或“参考”之意.例如： If you want to know his telephone number,you may refer to the telephone directory.如果你想知道他的电话号码，你可以查电话簿. 2.表示“谈到”或“提到”之意.例如： Please don't refer to his past again.请别再提他的往事了. The old soldier referred to his experiences during the Long March.老战士谈到了长征时的一些经历. 3.表示“适用于”或“涉及到”之意.例如： These books refer to Asian problems.这些书涉及到亚洲问题. These regulations refer only to children.这些规矩只适用于儿童. 三、refer to。
as。的用法.此短语意为“把……称作……”.例如： He is referred to as a living Lei Feng.他被称作是一个活雷锋.。
3.refer to的用法!
refer to
v.查阅， 提到， 谈到， 打听
refer to sth.
call
v.呼叫， 召集， 称呼， 认为， 命名， 打电话
This is morally referred to as the"direct write-off"method for receivables.
从精神上来说涉及到"一笔勾销"的方法是可接受的.
call好像扯不上关系。.
4.请告诉我refer to 的用法(说具体点,谢谢)
refer
[ri5fE:]
vt.
(referred; referring)
(1)
提交， 委托
(2)
把。归类[序， 因]于， 认为。是源于
(3)
谈[涉， 提]及， 提到， 指（的是）
(4)
参考[照]， 引证， 查阅， 用户访问
(5)
指点[引， 示]
(6)
折合
(7)
叫某人查阅[询]， 参看
refer a question to an expert
把问题提交给专家（处理）
the question referred to
所谈到的问题
refer sb. to the dictionary
叫某人去查字典
The invention of the compass is referred to China.
指南针是中国发明的。
The teacher referred him to Chapter V.
老师叫他看第五章。
The visitors are referred to the information desk.
让来访者到问事处去。
He referred his success to the good teaching he had had.
他把他的成功归于他以前所受的良好教育。
习惯用语
--------------------------------------------------------------------------------
refer oneself to
依赖， 求助于
refer to
(1)
提到， 谈到， 涉及
(2)
参考， 查阅
(3)
向。打听[查询]
(4)
认为与。有关， 认为。起源于。
refer to sb. [sth.] as
称某人[物]为
5.Refer to什么意思呀
refer to
音标百： 英 [rɪ'fɜː] 美 [rɪ'fɝ]
释义：参考；涉及；指的是；适用于
例句：
1.Refer to the original, please. 请参看原文。
2.Moreover, it lets you refer to another policy via the element. 此外，度它还允许您通过 元素引用另一个策略。
3.Jim records his workout so that he can refer to it and think about how he shouldimprove his workout the next day. 吉姆纪录他的锻知炼强度，使他可以作为参考，并思考接下来他该道怎么提高自己的训练水平。
6.python3.0怎么用json从文件解析
下面给出一个使用python解析json的简单例子：
#!/usr/bin/python
import json
#Function:Analyze json script
#Json is a script can descript data structure as xml,
#for detail, please refer to "".
#Note:
#1.Also, if you write json script from python,
#you should use dump instead of load. pleaser refer to "help(json)".
#json file:
#The file content of temp.json is:
#{
# "name":"00_sample_case1",
# "description":"an example."
#}
#f = file("temp.json");
#s = json.load(f)
#print s
#f.close
#json string:
s = json.loads('{"name":"test", "type":{"name":"seq", "parameter":["1", "2"]}}')
print s
print s.keys()
print s["name"]
print s["type"]["name"]
print s["type"]["parameter"][1]
7.如何用Python解析Json文件
更多的信息，可以参考python内部的json文档：
python>>> help(json)
或者官方文档：
#module-json
下面给出一个使用python解析json的简单例子：
#!/usr/bin/python
import json
#Function:Analyze json script
#Json is a script can descript data structure as xml,
#for detail, please refer to "".
#Note:
#1.Also, if you write json script from python,
#you should use dump instead of load. pleaser refer to "help(json)".
#json file:
#The file content of temp.json is:
#{
# "name":"00_sample_case1",
# "description":"an example."
#}
#f = file("temp.json");
#s = json.load(f)
#print s
#f.close
#json string:
s = json.loads('{"name":"test", "type":{"name":"seq", "parameter":["1", "2"]}}')
print s
print s.keys()
print s["name"]
print s["type"]["name"]
print s["type"]["parameter"][1]
8.python需要设置哪些环境变量
正常来说应该是可以什么都不用设置的，比如说你说的PYTHONHOME，这个不是需要你设置来指定一个目录的，而是当你需要修改默认目录的时候才应该修改这个环境变量，具体可以参考官方文档：PYTHONHOME Change the location of the standard Python libraries. By default, the libraries are searched in prefix/lib/pythonversion and exec_prefix/lib/pythonversion, where prefix and exec_prefix are installation-dependent directories, both defaulting to /usr/local.When PYTHONHOME is set to a single directory, its value replaces both prefix and exec_prefix. To specify different values for these, set PYTHONHOME to prefix:exec_prefix.PYTHONPATH Augment the default search path for module files. The format is the same as the shell's PATH: one or more directory pathnames separated by os.pathsep (e.g. colons on Unix or semicolons on Windows). Non-existent directories are silently ignored.In addition to normal directories, individual PYTHONPATH entries may refer to zipfiles containing pure Python modules (in either source or compiled form). Extension modules cannot be imported from zipfiles.The default search path is installation dependent, but generally begins with prefix/lib/pythonversion (see PYTHONHOME above). It is always appended to PYTHONPATH.An additional directory will be inserted in the search path in front of PYTHONPATH as described above under Interface options. The search path can be manipulated from within a Python program as the variable sys.path.PYTHONSTARTUP If this is the name of a readable file, the Python commands in that file are executed before the first prompt is displayed in interactive mode. The file is executed in the same namespace where interactive commands are executed so that objects defined or imported in it can be used without qualification in the interactive session. You can also change the prompts sys.ps1 and sys.ps2 in this file.PYTHONY2K Set this to a non-empty string to cause the time module to require dates specified as strings to include 4-digit years, otherwise 2-digit years are converted based on rules described in the time module documentation.PYTHONOPTIMIZE If this is set to a non-empty string it is equivalent to specifying the -O option. If set to an integer, it is equivalent to specifying -O multiple times.PYTHONDEBUG If this is set to a non-empty string it is equivalent to specifying the -d option. If set to an integer, it is equivalent to specifying -d multiple times.PYTHONINSPECT If this is set to a non-empty string it is equivalent to specifying the -i option.This variable can also be modified by Python code using os.environ to force inspect mode on program termination.PYTHONUNBUFFERED If this is set to a non-empty string it is equivalent to specifying the -u option.PYTHONVERBOSE If this is set to a non-empty string it is equivalent to specifying the -v option. If set to an integer, it is equivalent to specifying -v multiple times.PYTHONCASEOK If this is set, Python ignores case in import statements. This only works on Windows. If this is set, Python won't try to write .pyc or .pyo files on the import of source modules.New in version 2.6.PYTHONIOENCODING Overrides the encoding used for stdin/stdout/stderr, in the syntax encodingname:errorhandler. The :errorhandler part is optional and has the same meaning as in str.encode().New in version 2.6.PYTHONNOUSERSITE If this is set, Python won't add the user site-packages directory to sys.path.New in version 2.6.See also PEP 370 – Per user site-packages directory PYTHONUSERBASE Defines the user base directory, which is used to compute the path of the user site-packages directory and Distutils installation paths for python setup.py install --user.New in version 2.6.See also PEP 370 – Per user site-packages directory PYTHONEXECUTABLE If this environment variable is set, sys.argv[0] will be set to its value instead of the value got through the C runtime. Only works on Mac OS X.PYTHONWARNINGS This is equivalent to the -W option. If set to a comma separated string, it is equivalent to specifying -W multiple times.1.2.1. Debug-mode variables Setting these variables only has an effect in a debug build of Python, that is, if Python was configured with the --with-pydebug build option.PYTHONTHREADDEBUG If set, Python will print threading debug info.Changed in version 2.6: Previously, this variable was called THREADDEBUG.PYTHONDUMPREFS If set, Python will dump objects and reference counts still alive after shutting down the interpreter.PYTHONMALLOCSTATS If set, Python will print memory 。
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