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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...
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...
How can I force division to be floating point? Division keeps rounding down to 0?
...
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
>>...
Sorting 1 million 8-decimal-digit numbers with 1 MB of RAM
...
1
2
Next
720
...
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.
...
Redirect stderr and stdout in Bash
...
792
Take a look here. Should be:
yourcommand &>filename
(redirects both stdout and stderr ...
Import error: No module name urllib2
...
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...
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 ...
Java code To convert byte to Hexadecimal
...
byte[] bytes = {-1, 0, 1, 2, 3 };
StringBuilder sb = new StringBuilder();
for (byte b : bytes) {
sb.append(String.format("%02X ", b));
}
System.out.println(sb.toString());
// prints "FF 00 01 02 03 "
See also
java.util....
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 ...