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Can not connect to local PostgreSQL
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This really looks like a file permissions error. Unix domain sockets are files and have user permissions just like any other. It looks as though the OSX user attempting to access the database does not have file permissions to acce...
Signed to unsigned conversion in C - is it always safe?
...herwise, if the type of the operand with signed integer type can represent all of the values of the type of the operand with unsigned integer type, then the operand with unsigned integer type is converted to the type of the operand with signed integer type.
Otherwise, both operands are converted t...
appending array to FormData and send via AJAX
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add all type inputs to FormData
const formData = new FormData();
for (let key in form) {
Array.isArray(form[key])
? form[key].forEach(value => formData.append(key + '[]', value))
: formData.append(key, for...
Error installing mysql2: Failed to build gem native extension
I am having some problems when trying to install mysql2 gem for Rails. When I try to install it by running bundle install or gem install mysql2 it gives me the following error:
...
Apache Spark: map vs mapPartitions?
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I'm seeing the opposite -- even with very small operations, its faster to call mapPartitions and iterate than call map. I am assuming that this is just the overhead of starting the language engine that will process the map task. (I'm in R, which may have more startup...
What is the standard naming convention for html/css ids and classes?
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There isn't one.
I use underscores all the time, due to hyphens messing up the syntax highlighting of my text editor (Gedit), but that's personal preference.
I've seen all these conventions used all over the place. Use the one that you think is best - the one...
Python: Find in list
...e which suffers from inaccuracy.
As for your second question: There's actually several possible ways if "finding" things in lists.
Checking if something is inside
This is the use case you describe: Checking whether something is inside a list or not. As you know, you can use the in operator for th...
Why does the order in which libraries are linked sometimes cause errors in GCC?
...asier for the reader to see real command lines).
Common files shared by all below commands
$ cat a.cpp
extern int a;
int main() {
return a;
}
$ cat b.cpp
extern int b;
int a = b;
$ cat d.cpp
int b;
Linking to static libraries
$ g++ -c b.cpp -o b.o
$ ar cr libb.a b.o
$ g++ -c d.cpp -o d.o
...
Neo4j - Cypher vs Gremlin query language
...her the engine tries to find the best traversing solution itself.
I personally use Cypher because of its simplicity and, to date, I have not had any situations where I had to use Gremlin (except working with Gremlin graphML import/export functions). I expect, however, that even if i would need to u...
How can I determine whether a 2D Point is within a Polygon?
...integers. Many systems use integers for UI painting (pixels are ints after all), but macOS for example uses float for everything. macOS only knows points and a point can translate to one pixel, but depending on monitor resolution, it might translate to something else. On retina screens half a point ...