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Hidden features of C
...
Multi-character constants:
int x = 'ABCD';
This sets x to 0x41424344 (or 0x44434241, depending on architecture).
EDIT: This technique is not portable, especially if you serialize the int.
However, it can be extremely useful to ...
What is a good Hash Function?
... that differ only in the last 4 bytes can collide easily. If you have a 30 character string, that differ in the last 4 bytes, after 28 bytes have been processes, the hashes differ only in the last 2 bytes. That means you are GUARANTEED a collision for one of the remaining two-byte values. (Yeah, it'...
No visible cause for “Unexpected token ILLEGAL”
...e error is raised if, for example, you try to run a js file with a rogue @ character, a misplaced curly brace, bracket, "smart quotes", single quotes not enclosed properly (e.g. this.run('dev1)) and so on.
A lot of different situations can cause this error. But if you don't have any obvious syntax ...
Why does Git treat this text file as a binary file?
... inspected the file's contents it has seen stuff that isn't in basic ascii characters. Being UTF16 I expect that it will have 'funny' characters so it thinks it's binary.
There are ways of telling git if you have internationalisation (i18n) or extended character formats for the file. I'm not suffic...
Python int to binary string?
...ring type. Maybe a language where all strings are stored backwards or each char is a node in a linked list? For any typical language a string is basically an array of chars. In that case prefixing a string requires that a copy is made, how else are you going to put the character before the other cha...
What are the underlying data structures used for Redis?
...m-ish unique users") or with replacement ("give me 7 cards, but after each selection, put the card back so it can potentially be sampled again").
For all possible operations on sets, see the sets docs.
Sorted Sets
Redis sorted sets are sets with a user-defined ordering.
For simplicity, you can think...
Escape double quotes in parameter
...ve all the quotes here and place the parameter value in a string used in a select query filter? Can someone help?
– SFDC_Learner
Nov 24 '15 at 16:21
...
Polymorphism in C++
...egorise them in various ways:
When is the polymorphic type-specific code selected?
Run time means the compiler must generate code for all the types the program might handle while running, and at run-time the correct code is selected (virtual dispatch)
Compile time means the choice of type-specif...
Check if a string contains another string
...ontains a ","(comma) in it. Do we have any other option other than reading char-by-char?
4 Answers
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Replacing a 32-bit loop counter with 64-bit introduces crazy performance deviations with _mm_popcnt_
...;
#include <chrono>
#include <x86intrin.h>
int main(int argc, char* argv[]) {
using namespace std;
uint64_t size=1<<20;
uint64_t* buffer = new uint64_t[size/8];
char* charbuffer=reinterpret_cast<char*>(buffer);
for (unsigned i=0;i<size;++i) charbuffer[i]=...