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RSS订阅原创 Shell Parameter Expansion
http://stackoverflow.com/questions/12671406/bash-removing-part-of-a-string [code="bash"] var="Memory Used: 19.54M" var=${var#*: } # Remove everything up to a colon and space var=${var...
2016-01-16 13:30:22
277
原创 lost on Py_DECREF/INCREF when handling PyList_Append in Python C extension
The main hint is in the docs, if it says 'Steals a reference' than the function basically takes ownership, if it says 'New Reference' than it did an INCREF for you, if nothing is said it probably does...
2015-11-03 21:41:16
305
原创 How can I convert a character to a integer in Python, and viceversa?
Use chr() and ord(): >>> chr(97) 'a' >>> ord('a') 97
2015-10-27 14:38:04
275
原创 How to build a Ruby hash out of two equally-sized arrays?
ruby-doc.org/core-2.1.2/String.html
2014-09-03 15:54:20
164
原创 typedef struct in c
typedef struct atom { int element; struct atom *next; }; vs. typedef struct { int element; struct atom *next; } atom; http://stackoverflow.com/questions/18806392/typedef-struct-...
2014-04-29 16:18:06
214
原创 An Example of Using std::tr1::bind
[code="c++"] #include #include using std::tr1::bind; using std::tr1::function; using std::tr1::placeholders::_1; using std::tr1::placeholders::_2; class CTest { public: ...
2014-03-10 16:49:28
155
原创 c++中的virtual inheritance
[url]http://stackoverflow.com/questions/21558/in-c-what-is-a-virtual-base-class[/url] 主要是为了避免歧义。
2014-01-27 10:20:19
194
原创 C中的宏 [Macro in C]
最近在学习c，话说从java转向c真的蛮痛苦。Anyway，学习就是一份好经历。 看到如下一段code： [code="c"] #define APP_TOOL_OP_TYPES(f) \ f(SIMPLE, "simple", FALSE) \ f(JSON, "json", TRUE) ...
2014-01-26 10:04:47
189
原创 Java NIO
看了这个java nio的教程，明白了什么是Selector.wakeUp() [url]http://ifeve.com/selectors/[/url] wakeUp() 某个线程调用select()方法后阻塞了，即使没有通道已经就绪，也有办法让其从select()方法返回。只要让其它线程在第一个线程调用select()方法的那个对象上调用Selector.wakeup()方...
2014-01-10 21:28:06
134
hadoop-2.2.0 build failure due to missing dependancy
The bug and fix is at https://issues.apache.org/jira/browse/HADOOP-10110
2014-01-06 13:18:18
130
原创 java i18n exception
http://www.cab.u-szeged.hu/WWW/java/tutorial/i18n/exception/subclass.html
2013-11-11 17:37:39
355
flume build过程中出现Too many unapproved licenses错误
在target/rat.txt下面寻找哪些文件前面打了问号，去掉这些文件！
2013-09-22 21:31:18
551
perl tips for qw qq qx q
q// is generally the same thing as using single quotes - meaning it doesn't interpolate values inside the delimiters. qq// is the same as double quoting a string. It interpolates. qw// return a list...
2013-07-26 16:58:02
173
原创 show git branch in your bash prompt
export PS1='\[\e[1;0m\][\[\e[38;5;174m\]\u\[\e[38;5;240m\]@\[\e[01;32m\]\h\[\e[38;5;222m\] \w\[\e[31m\]$(parse_git_branch "(%s)")\[\e[1;0m\]]\[\e[38;5;240m\]\$\[\e[1;0m\]\e[m' function parse_git_br...
2013-07-26 16:47:26
333
原创 Show git log history in beautiful format
git alias: lg = log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)%Creset' --abbrev-commit --date=relative
2013-07-26 15:44:21
157
原创 再谈Java的wait(), sleep(), notify()和notifyAll()
一段时间不用java，这些概念就全混淆了，有必要彻底澄清一下，总结在这里，当然以我的本事，不太可能写出水平较高的总结，这里主要是总结stackoverflow上面高人的言论。 [u][b]先说sleep() 和 wait()[/b][/u] [b]sleep()[/b] method causes the current thread to move from running stat...
2013-07-25 10:59:45
124
shell字符串截取
${string#substring} 从string左边去掉第一个substring ${string%substring} 从string右边去掉第一个substring
2013-07-19 15:09:32
131
原创 ubuntu 安装 java 环境
本人安装的是oracle java6 1. 下载jre wget --no-cookies --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F" http://download.oracle.com/otn-pub/java/jdk/6u45-b06/jre-6u45-linux-x64.bin 2. 下载jdk ...
2013-07-07 12:38:51
134
原创 ubuntu 安装中文输入法
1. 安装语言包 System Settings-->Language Support-->Install/Remove Languages => 安装Chinese（simplified） 2. 安装IBus框架 sudo apt-get install ibus ibus-clutter ibus-gtk ibus-gtk3 ibus-qt4 3. 启动IBus框架 im-switc...
2013-07-07 10:57:44
188
Why singleton is anti-pattern?
[list] [*] OO [*] Test [*] Other reasons? [/list]
2013-07-03 10:12:40
165
原创 How to generate the serialVersionUID when you implement Serializable interface,j
[url]http://docs.oracle.com/javase/6/docs/technotes/tools/solaris/serialver.html[/url]
2013-07-01 10:52:40
98
Serialize/Deserialize Perl Class Objects
Today in a small project I need to serialize a perl class object to string in order to cache it. And when getting back the value from the cache I need to deserialize it to original class objects. ...
2013-06-18 14:09:16
118
原创 Java Override的两个问题
1： 如果子类中的方法的参数是父类的方法的子类型，那么算不算override？ 例如： [code="java"]class A { public void foo(A a){ } } class B extends A { public void foo(B b){ } }[/code] 2：如果子类中的方法的返回类型改变了，那么算不算override？ ...
2013-06-01 11:40:57
127
原创 How many string objects are created?
This is a very common java interview question. Given the following: String x = new String("xyz"); y="abc"; x=x+y; How Many Strings have been created: A - 2 B - 3 C - 4 D - ...
2013-06-01 10:18:48
194
使用Java的DelayQueue容易碰到的一个坑
今天不忙，学习一下java.util.concurrent.DelayQueue这个类的使用。参照了 [url]http://www.concretepage.com/java/example_delayqueue_java.php[/url] 上的例子，但是这里有个坑。 先看一下整个code吧： [code="java"] import java.util.concurrent...
2013-05-27 17:32:25
938
原创 HBase Schema Design
As someone has said [url=http://www.stephenonsoftware.com/2012/06/hbase-schema-design.html]here[/url] [quote]You need to look more at the types of queries that you will be needing to access your da...
2013-05-24 11:41:20
148
原创 use "--links" option of rsync
Today I used rsync to copy some files but I found for symbolic links it will ignore them if you just use simple command line: rsync SRC DEST With google, I finally figure out I need to add the "...
2013-05-23 10:45:25
139
Question on HBase source code
I'm reading source code of hbase. When come to class org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher I find this class has private member *unassignedNodes* but I cannot find where nodes are added i...
2013-05-22 15:05:16
117
原创 Using the libjars option with Hadoop
As I have said in my last post, I was developing a hbase based mapreduce application. But one damn thing is the hadoop cluster managed by our system admin has no hbase jars in its classpath... So I...
2013-05-20 15:03:23
148
Use HBase to Solve Page Access Problem
Currrently I'm working on sth like calculating how many hits on a page. The problem is the raw data can be huge, so it may not scale if you use RDBMS. The raw input is as follows. Date Page Use...
2013-05-17 14:48:31
134
原创 Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/thi
If you meet this exception, make sure you include the guava-r09-jarjar.jar JAR in your build path. This is usually located in /usr/lib/hadoop-0.20/lib.
2013-05-16 15:27:09
378
[leetcode] Decode ways
[url]http://leetcode.com/onlinejudge#question_91[/url] Decode WaysJun 25 '121292 / 5011 A message containing letters from A-Z is being encoded to numbers using the following mapping: 'A' -> 1 'B...
2013-05-02 21:47:39
121
原创 [leetcode] Balanced Binary Tree
Check if a binary tree is balanced or not. This solution is from the discuss board. Much better than mine. [code="java"] /** * Definition for binary tree * public class TreeNode { * int ...
2013-04-28 14:08:57
132
[leetcode] find median of two sorted arrays
[url]http://leetcode.com/onlinejudge#question_4[/url] Solution: a little ugly. [code="java"] public class Solution { public double findMedianSortedArrays(int A[], int B[]) { /...
2013-04-26 10:55:02
128
[leetcode] word ladder
Q: Given two words (start and end), and a dictionary, find the length of shortest transformation sequence from start to end, such that: Only one letter can be changed at a time Each inter...
2013-04-25 15:05:24
137
[leetcode] sqrt(x)
I have talked about this question in my previous posts. http://leetcode.com/onlinejudge#question_69 Q: Implement int sqrt(int x). Compute and return the square root of x. Solution: [code...
2013-04-15 07:44:01
128
[leetcode] word ladder II
http://leetcode.com/onlinejudge#question_126 Q: Given two words (start and end), and a dictionary, find all shortest transformation sequence(s) from start to end, such that: Only one let...
2013-04-15 07:35:45
8245
原创 [leetcode] Count and Say
http://leetcode.com/onlinejudge#question_38 Question: The count-and-say sequence is the sequence of integers beginning as follows: 1, 11, 21, 1211, 111221, ... 1 is read off as "one 1" or 11...
2013-04-12 14:05:02
125
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