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How does having a dynamic variable affect performance?
...method we call were trying to do something intensive, like combining a few strings together or searching a collection for a value, those operations would likely far outweigh the difference between a direct call and a dynamic call.
Performance is just one of many good reasons not to use dynamic unnec...
Delete all but the most recent X files in bash
... handle NUL-separated input, after first translating newlines to NUL (0x0) chars., which also passes (typically) all filenames at once (will also work with GNU xargs):
ls -tp | grep -v '/$' | tail -n +6 | tr '\n' '\0' | xargs -0 rm --
Explanation:
ls -tp prints the names of filesystem items sor...
HTML for the Pause symbol in audio and video control
...y default) in order to instruct the parser how to transform the bytes into characters correctly. <meta charset="utf-8"/> should be used immediately after <head> in a HTML file, and make sure the correct HTTP headers Content-Type: text/html; charset=utf-8 are set.
Examples:
HTML
&...
What is the difference between a 'closure' and a 'lambda'?
...l these free symbols by binding them to some values (which may be numbers, strings, anonymous functions aka lambdas, whatever…).
And here comes the closure part:
The closure of a lambda expression is this particular set of symbols defined in the outer context (environment) that give values to the...
How to generate a random int in C?
...
If you need secure random characters or integers:
As addressed in how to safely generate random numbers in various programming languages, you'll want to do one of the following:
Use libsodium's randombytes API
Re-implement what you need from libsod...
Converting a Java Keystore into PEM Format
...
KeyStore ks = KeyStore.getInstance("jks");
/* Load the key store. */
...
char[] password = ...;
/* Save the private key. */
FileOutputStream kos = new FileOutputStream("tmpkey.der");
Key pvt = ks.getKey("your_alias", password);
kos.write(pvt.getEncoded());
kos.flush();
kos.close();
/* Save the cer...
How to generate a random number in C++?
...in a random generator in this way:
#include <iostream>
#include <string>
// Used in randomization
#include <ctime>
#include <boost/random/mersenne_twister.hpp>
#include <boost/random/uniform_int_distribution.hpp>
#include <boost/random/variate_generator.hpp>
us...
What is the most efficient/elegant way to parse a flat table into a tree?
... sets (sometimes referred to as Modified Pre-order Tree Traversal) you can extract the entire tree structure or any subtree within it in tree order with a single query, at the cost of inserts being more expensive, as you need to manage columns which describe an in-order path through thee tree struct...
Creating JS object with Object.create(null)?
... in the map that you never inserted. For example, if you did a lookup on toString, you would find a function, even though you never put that value there. You can work around that like this:
if (Object.prototype.hasOwnProperty.call(p, 'toString')) {
// we actually inserted a 'toString' key into p...
What is the easiest way to initialize a std::vector with hardcoded elements?
...typesafe, compile time constant
template <typename T, std::size_t N>
char (&sizeof_array( T(&)[N] ))[N]; // declared, undefined
#define ARRAY_SIZE(x) sizeof(sizeof_array(x))
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