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Subqueries vs joins
...mple of how subqueries are evaluated in MySQL 6.0.
The new optimizer will convert this kind of subqueries into joins.
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How do I count unique values inside a list
...s are thrown away, and list.count() is O(n) anyway. You don't even need to convert aa to list at all. See Vidul's answer instead.
– wjandrea
Sep 23 at 15:38
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What is the curiously recurring template pattern (CRTP)?
...ts specialization for any type X will be inherited from singleton<X> and thus will have all its (public, protected) members accessible, including the GetInstance! There are other useful uses of CRTP. For example, if you want to count all instances that currently exist for your class, but want ...
Is there a Python function to determine which quarter of the year a date is in?
...ed to count from 1 instead;-).
Originally two answers, multiply upvoted and even originally accepted (both currently deleted), were buggy -- not doing the -1 before the division, and dividing by 4 instead of 3. Since .month goes 1 to 12, it's easy to check for yourself what formula is right:
fo...
fastest (low latency) method for Inter Process Communication between Java and C/C++
... passing a single byte with code like this:
MappedByteBuffer mem =
new RandomAccessFile("/tmp/mapped.txt", "rw").getChannel()
.map(FileChannel.MapMode.READ_WRITE, 0, 1);
while(true){
while(mem.get(0)!=5) Thread.sleep(0); // waiting for client request
mem.put(0, (byte)10); // sending the re...
array_push() with key value pair
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Warning: $a['123'] = 456; - string '123' is converted to integer key 123.
– bancer
Jul 2 at 12:58
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Parse XML using JavaScript [duplicate]
..., asked 20 minutes before this one, that you are trying to parse (read and convert) the XML found through using GeoNames' FindNearestAddress.
If your XML is in a string variable called txt and looks like this:
<address>
<street>Roble Ave</street>
<mtfcc>S1400</mtfcc&...
Is it intended by the C++ standards committee that in C++11 unordered_map destroys what it inserts?
...behaviour occurs in very recent compilers only: I found that clang 3.2-3.4 and GCC 4.8 are the only compilers to demonstrate this "feature".
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How do I restrict a float value to only two places after the decimal point in C?
...e: round down (ie, truncate after two decimal places), rounded to nearest, and round up. Usually, you want round to nearest.
As several others have pointed out, due to the quirks of floating point representation, these rounded values may not be exactly the "obvious" decimal values, but they will b...
Why is the order in dictionaries and sets arbitrary?
I don't understand how looping over a dictionary or set in python is done by 'arbitrary' order.
6 Answers
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