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How do you declare an interface in C++?
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To expand on the answer by bradtgmurray, you may want to make one exception to the pure virtual method list of your interface by adding a virtual destructor. This allows you to pass pointer ownership to another party without expos...
MySQL CONCAT returns NULL if any field contain NULL
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convert the NULL values with empty string by wrapping it in COALESCE
SELECT CONCAT(COALESCE(`affiliate_name`,''),'-',COALESCE(`model`,''),'-',COALESCE(`ip`,''),'-',COALESCE(`os_type`,''),'-',COALESCE(`os_version`,'')) AS dev...
How to assign colors to categorical variables in ggplot2 that have stable mapping?
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The easiest solution is to convert your categorical variable to a factor prior to the subsetting. Bottomline is that you need a factor variable with exact the same levels in all your subsets.
library(ggplot2)
dataset <- data.frame(category = rep(LE...
What is the purpose of the word 'self'?
... class.
Now when ObjectA.methodA(arg1, arg2) is called, python internally converts it for you as:
ClassA.methodA(ObjectA, arg1, arg2)
The self variable refers to the object itself.
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Can you split a stream into two streams?
...ou think it is ... stream.boxed().collect(...);! It will do as advertised: convert the primitive IntStream to the boxed Stream<Integer> version.
– YoYo
May 8 '15 at 3:57
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Simulate CREATE DATABASE IF NOT EXISTS for PostgreSQL?
...cate_database exception (which is issued when database already exists) and converts it into notice with propagating errcode. String message has appended , skipping in the same way how it does CREATE SCHEMA IF NOT EXISTS.
CREATE EXTENSION IF NOT EXISTS dblink;
DO $$
BEGIN
PERFORM dblink_exec('', 'C...
Why does parseInt yield NaN with Array#map?
...seInt: it doesn't parse the string and returns NaN if the number cannot be converted. For instance:
console.log(parseInt("19asdf"));
console.log(Number("19asf"));
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URL encoding the space character: + or %20?
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And the URLEncoder.encode() method in Java converts it in + as well.
– рüффп
Oct 24 '14 at 12:48
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How does the following LINQ statement work?
...conversion operators which allow you to make a copy/snapshot of the result and access is as many times you want, without the need to re-execute the query.
If you want the output to be 2,4,6, use .ToList():
var list = new List<int>{1,2,4,5,6};
var even = list.Where(m => m%2 == 0).ToList()...
Importing a GitHub project into Eclipse
...lso had to right-click on project > Properties > Project Facets > Convert to faceted form
– xtian
Sep 29 '15 at 9:49
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