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Extracting the last n characters from a ruby string
...a one liner, you can put a number greater than the size of the string:
"123".split(//).last(5).to_s
For ruby 1.9+
"123".split(//).last(5).join("").to_s
For ruby 2.0+, join returns a string
"123".split(//).last(5).join
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Ways to save enums in database
...me :
public enum Suit {
Unknown = 4,
Heart = 1,
Club = 3,
Diamond = 2,
Spade = 0 }
in order to maintain the legacy numerical values stored in the database.
How to sort them in the database
The question comes up: lets say i wanted to order the values. Some people m...
Base64: What is the worst possible increase in space usage?
...the size of the base-64 representation of a string of size n is:
ceil(n / 3) * 4
So, for a 16kB array, the base-64 representation will be ceil(16*1024/3)*4 = 21848 bytes long ~= 21.8kB.
A rough approximation would be that the size of the data is increased to 4/3 of the original.
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linux 下巧妙使用squid代理服务器 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...点。
1．共享网络
2．加快访问速度，节约通信带宽
3．防止内部主机受到攻击
4．限制用户访问，完善网络管理
原理：
① 客户端A向代理服务器提出访问Internet的请求。
② 代理服务器接受到请求后，首先与访问控制列...
Approximate cost to access various caches and main memory?
...anyone give me the approximate time (in nanoseconds) to access L1, L2 and L3 caches, as well as main memory on Intel i7 processors?
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What is the fastest method for selecting descendant elements in jQuery?
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3 Answers
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Active
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How to distinguish between left and right mouse click with jQuery
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As of jQuery version 1.1.3, event.which normalizes event.keyCode and event.charCode so you don't have to worry about browser compatibility issues. Documentation on event.which
event.which will give 1, 2 or 3 for left, middle and right mouse buttons ...
C语言结构体里的成员数组和指针 - C/C++ - 清泛网 - 专注C/C++及内核技术
...去编译和调试，我把代码列在下面：
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#include <stdio.h>
struct str{
int len;
char s[0];
};
struct foo {
struct str *a;
};
int main(int argc, char** arg...
Django REST framework: non-model serializer
...ork will take care of the serialization for you.
You can skip steps 2 and 3 in this case, and just use one class for calculations and one for presentation to the API consumer.
Here are a few snippets may help you out:
Please note that I have not tested this. It's only meant as an example, but it ...