大约有 45,200 项符合查询结果（耗时：0.0286秒） [XML]
What is the difference between Ruby 1.8 and Ruby 1.9
..."cat"[1]
=> 97
{"a","b"} No Longer Supported
Ruby 1.9
irb(main):002:0> {1,2}
SyntaxError: (irb):2: syntax error, unexpected ',', expecting tASSOC
Ruby 1.8.6
irb(main):001:0> {1,2}
=> {1=>2}
Action: Convert to {1 => 2}
Array.to_s Now Contains Punctuation
Ruby 1.9
irb...
How can I force division to be floating point? Division keeps rounding down to 0?
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In Python 2, division of two ints produces an int. In Python 3, it produces a float. We can get the new behaviour by importing from __future__.
>>> from __future__ import division
>>> a = 4
>>> b = 6
>>...
What's the difference between equal?, eql?, ===, and ==?
...
+200
I'm going to heavily quote the Object documentation here, because I think it has some great explanations. I encourage you to read it...
Import error: No module name urllib2
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As stated in the urllib2 documentation:
The urllib2 module has been split across several modules in Python 3 named urllib.request and urllib.error. The 2to3 tool will automatically adapt imports when converting your sources to Python 3.
So yo...
Splitting a list into N parts of approximately equal length
... equal parts? For example, if the list has 7 elements and is split it into 2 parts, we want to get 3 elements in one part, and the other should have 4 elements.
...
Sorting 1 million 8-decimal-digit numbers with 1 MB of RAM
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1
2
Next
720
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Redirect stderr and stdout in Bash
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792
Take a look here. Should be:
yourcommand &>filename
(redirects both stdout and stderr ...
Are tuples more efficient than lists in Python?
... is much faster than assigning a list.
>>> def a():
... x=[1,2,3,4,5]
... y=x[2]
...
>>> def b():
... x=(1,2,3,4,5)
... y=x[2]
...
>>> import dis
>>> dis.dis(a)
2 0 LOAD_CONST 1 (1)
3 LOAD_CONST ...
MongoDB数据导出导入工具：mongoexport,mongoimport - 大数据 & AI - 清泛...
...xit
-h [ --host ] arg mongo host to connect to ( <set name>/s1,s2 for sets)
--port arg server port. Can also use --host hostname:port
--ipv6 enable IPv6 support (disabled by default)
-u [ --username ] arg username
-p [ --password ] arg ...
What is the reason for having '//' in Python? [duplicate]
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527
In Python 3, they made the / operator do a floating-point division, and added the // operator t...