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Virtual functions and performance - C++
...an instruction cache miss like a non-virtual function.
In many cases, two extra cache misses are not a concern, but in a tight loop on performance critical code it can dramatically reduce performance.
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Best way to store password in database [closed]
...note that a common misconception is to simply add the same unique and long string to all passwords; while this is not horrible, it is best to add unique salts to every password. Read this for more.
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MongoDB with redis
...fit from the flexibility of MongoDB for main persistent data, and from the extra features provided by Redis (low latency, item expiration, queues, pub/sub, atomic blocks, etc ...). It is indeed a good combination.
Please note you should never run a Redis and MongoDB server on the same machine. Mong...
Centering a div block without the width
...S rule. This is a good trick to center a div in a container without adding extra HTML nor applying constraining styles to the container (like text-align: center; which would center all other inline content in the container), while keeping dynamic width for the contained div:
HTML:
<div class="c...
Why does SIGPIPE exist?
...d.h>
# include <stdio.h>
# include <signal.h>
# include <string.h>
int writeCount = 0;
void sighandler(int sig) {
char buf1[30] ;
sprintf(buf1,"signal %d writeCount %d\n", sig, writeCount);
ssize_t leng = strlen(buf1);
write(2, buf1, leng);
_exit(1);
}
...
How do I push amended commit to the remote Git repository?
... .git/config branch section).
And after
git push
Maybe you will get an extra commit with the subject telling about a "Trivial merge".
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What are the best practices for SQLite on Android?
... new AtomicInteger(0);
public DBSQLiteOpenHelper(Context context, String name, int version, DatabaseManager databaseManager) {
super(context, name, null, version);
this.databaseManager = databaseManager;
}
public void addConnection(){
cou...
Why is “while ( !feof (file) )” always wrong?
... stream is still in the good() state.
C++, iostreams getline:
for (std::string line; std::getline(std::cin, line); ) {
consume(line);
}
The result we must use is again std::cin, just as before.
POSIX, write(2) to flush a buffer:
char const * p = buf;
ssize_t n = bufsize;
for (ss...
What is offsetHeight, clientHeight, scrollHeight?
...omething that resides inside of the HTML container, so it doesn't count as extra measurements like margin or border. So :
clientHeight property returns the viewable height of an element in
pixels, including padding, but not the border, scrollbar or margin.
ScrollHeight is all the scrol...
NodeJS - Error installing with NPM
...t least) 2 ways to resolve this.
Installing the Cygwin package cygutils-extra and use winln.
Use native Windows CMD in Admin mode.
For (1) you can create a proper symlink from within Cygwin shell by doing these steps:
# To make the Cygwin environment treat Windows links properly:
# Alternat...