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When is assembly faster than C?
...igh part of 64 bit integer multiplication: A portable version using uint64_t for 32x32 => 64-bit multiplies fails to optimize on a 64-bit CPU, so you need intrinsics or __int128 for efficient code on 64-bit systems.
_umul128 on Windows 32 bits: MSVC doesn't always do a good job when multiplying ...
What is the effect of extern “C” in C++?
...n it posted yet.
You'll very often see code in C headers like so:
#ifdef __cplusplus
extern "C" {
#endif
// all of your legacy C code here
#ifdef __cplusplus
}
#endif
What this accomplishes is that it allows you to use that C header file with your C++ code, because the macro "__cplusplus" will...
C# Lazy Loaded Automatic Properties
... 4.0 Lazy<T> type to create this pattern
private Lazy<string> _someVariable =new Lazy<string>(SomeClass.IOnlyWantToCallYouOnce);
public string SomeVariable => _someVariable.Value;
This code will lazily calculate the value of _someVariable the first time the Value expression i...
Matplotlib: “Unknown projection '3d'” error
...e you using? (Try running: python -c 'import matplotlib; print matplotlib."__version__")
I'm guessing you're running version 0.99, in which case you'll need to either use a slightly different syntax or update to a more recent version of matplotlib.
If you're running version 0.99, try doing this in...
What is Bit Masking?
...esult: 00000101b
Masking is implemented using AND, so in C we get:
uint8_t stuff(...) {
uint8_t mask = 0x0f; // 00001111b
uint8_t value = 0x55; // 01010101b
return mask & value;
}
Here is a fairly common use-case: Extracting individual bytes from a larger word. We define the high-...
C++ project organisation (with gtest, cmake and doxygen)
...asy is the dependency to install on their
platform. CMake comes with a find_package script for Google
Test. This makes things a lot easier. I would go with bundling only
when necessary and avoid it otherwise.
How to build: Avoid in-source builds. CMake makes out of source-builds
easy and it makes l...
What are 'closures' in .NET?
...thod and the variable j
[CompilerGenerated]
private sealed class <>c__DisplayClass2
{
public <>c__DisplayClass2();
public void <fillFunc>b__0()
{
Console.Write("{0} ", this.j);
}
public int j;
}
for the function:
static void fillFunc(int count) {
...
Adding information to an exception?
....message +
' happens at %s' % arg1), sys.exc_info()[2]
bar('arg1')
Traceback (most recent call last):
File "test.py", line 16, in <module>
bar('arg1')
File "test.py", line 11, in bar
foo()
File "test.py", line 5, in foo
raise IOError('Stuff...
Cross-Origin Request Headers(CORS) with PHP headers
...nitty-gritty low-down, read:
*
* - https://developer.mozilla.org/en/HTTP_access_control
* - http://www.w3.org/TR/cors/
*
*/
function cors() {
// Allow from any origin
if (isset($_SERVER['HTTP_ORIGIN'])) {
// Decide if the origin in $_SERVER['HTTP_ORIGIN'] is one
// yo...
What happens to global and static variables in a shared library when it is dynamically linked?
...yntax similar to the function export/import syntax, i.e.:
#ifdef COMPILING_THE_DLL
#define MY_DLL_EXPORT extern "C" __declspec(dllexport)
#else
#define MY_DLL_EXPORT extern "C" __declspec(dllimport)
#endif
MY_DLL_EXPORT int my_global;
When you do that, the global variable is added to the list of...