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List of Big-O for PHP functions
...all: Thanks! I did a bit of reading and it turns out PHP uses 'nested' hashtables for collisions. That is, instead of a logn structure for collisions it simply uses another hashtable. And I do understand that practically speaking PHP hashtables give O(1) performance, or at least O(1) on average - t...
JavaScript for…in vs for
...uff with o[key]
Unless you have earth shattering reasons, stick to the established pattern of usage.
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Why is XOR the default way to combine hashes?
... uniform probability distributions.
This can be seen by writing out truth tables:
a | b | a AND b
---+---+--------
0 | 0 | 0
0 | 1 | 0
1 | 0 | 0
1 | 1 | 1
a | b | a OR b
---+---+--------
0 | 0 | 0
0 | 1 | 1
1 | 0 | 1
1 | 1 | 1
a | b | a XOR b
---+---+--------
...
SQLite UPSERT / UPDATE OR INSERT
... there are two ways to accomplish this, depending on the structure of your table and if you have foreign keys restrictions activated to maintain integrity. I'd like to share this in a clean format to save some time to the people that may be in my situation.
Option 1: You can afford deleting the row...
MySQL/SQL: Group by date only on a Datetime column
Having a table with a column like: mydate DATETIME ...
4 Answers
4
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How to $http Synchronous call with AngularJS
...model="search"></input>
<div class="bs-example">
<table class="table" >
<thead>
<tr>
<th>#</th>
<th>Description</th>
</tr>
</thead>
<tbody>
...
Test for non-zero length string in Bash: [ -n “$var” ] or [ “$var” ]
...on that shows more differences between [ (aka test) and [[.
The following table shows that whether a variable is quoted or not, whether you use single or double brackets and whether the variable contains only a space are the things that affect whether using a test with or without -n/-z is suitable ...
TSQL - Cast string to integer or return default value
...> 2147483647 RETURN NULL
RETURN @I
END
GO
-- Testing
DECLARE @Test TABLE(Value nvarchar(50)) -- Result
INSERT INTO @Test SELECT '1234' -- 1234
INSERT INTO @Test SELECT '1,234' -- 1234
INSERT INTO @Test SELECT '1234.0' -- 1234
INSERT INTO @Test SELECT '-1234' ...
Checking if a SQL Server login already exists
...ction. Attacker can pass a @loginName like x] with password ''y'';\r\ndrop table foo;\r\n
– Remus Rusanu
Sep 4 '09 at 14:47
2
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C++ performance challenge: integer to std::string conversion
... first one is a fun implementation that doesn't use any precomputed lookup tables or explicit division/modulo. This one is competitive with the others with gcc and with all but Timo's on msvc (for a good reason that I explain below). The second algorithm is my actual submission for highest performan...