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Why does GCC generate 15-20% faster code if I optimize for size instead of speed?
...t z = add(x, y);
sum += z;
}
return sum;
}
int main(int , char* argv[]) {
int result = work(*argv[1], *argv[2]);
return result;
}
and compiled as: g++ -O2 add.cpp main.cpp.
gcc won't inline add()!
That's all, it's that easy to unintendedly create hotspots l...
How to generate a random number in C++?
...me(CLOCK_REALTIME, &tm);
return tm.tv_nsec;
}
int main (int argc, char* argv[]) {
unsigned int dice_rolls = 12;
random::mt19937 rng(current_time_nanoseconds());
random::uniform_int_distribution<> six(1,6);
for(unsigned int i=0; i<dice_rolls; i++){
cout <...
What are the Dangers of Method Swizzling in Objective-C?
... class_getInstanceMethod(class, original);
if (method) {
const char *type = method_getTypeEncoding(method);
imp = class_replaceMethod(class, original, replacement, type);
if (!imp) {
imp = method_getImplementation(method);
}
}
if (imp &&...
What encoding/code page is cmd.exe using?
...rograms
print gibberish, and sometimes they do not.
First of all, Unicode characters will only display if the
current console font contains the characters. So use
a TrueType font like Lucida Console instead of the default Raster Font.
But if the console font doesn’t contain the character you’r...
How can I efficiently select a Standard Library container in C++11?
... well known image (cheat sheet) called "C++ Container choice". It's a flow chart to choose the best container for the wanted usage.
...
Regex Pattern to Match, Excluding when… / Except between
...)/ trick regex would be something like: /"[^"]*"|Tarzan/ (ignoring escaped chars). This will work for many cases, but fails completely when applied to the following valid JavaScript text: var bug1 = 'One " quote here. Should match this Tarzan'; var bug2 = "Should not match this Tarzan";. Rex's trick...
Move capture in lambda
...ts> // for std::result_of
#include <cstddef>
void showPtr(const char* name, const std::unique_ptr<size_t>& ptr)
{
std::cout << "- &" << name << " = " << &ptr << ", " << name << ".get() = "
<< ptr.get();
...
Java 256-bit AES Password-Based Encryption
...
Share the password (a char[]) and salt (a byte[]—8 bytes selected by a SecureRandom makes a good salt—which doesn't need to be kept secret) with the recipient out-of-band. Then to derive a good key from this information:
/* Derive the key, gi...
Swift Beta performance: sorting arrays
...sing namespace std;
using namespace std::chrono;
int main(int argc, const char * argv[]) {
const auto arraySize = 10000000;
vector<uint32_t> randomNumbers;
for (int i = 0; i < arraySize; ++i) {
randomNumbers.emplace_back(arc4random_uniform(arraySize));
}
const...
How to parse freeform street/postal address out of text, and into components
...ostal code may be omitted even if has city & state
- state may be two-char code or may be full state name.
- commas:
-- last comma is usually city/state separator
-- second-to-last comma is possibly street/city separator
-- other commas are building-specific stuff that I don't care about r...