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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]=...
How many GCC optimization levels are there?
...rst part of this function:
does integral_argument which calls atoi on the string corresponding to OPT_O to parse the input argument
stores the value inside opts->x_optimize where opts is a struct gcc_opts.
struct gcc_opts
After grepping in vain, we notice that this struct is also generated at ...
What is the difference between g++ and gcc?
...
The spec strings are constructed to be specific to the compiler, which in turn are specific to the operating system and target. So if you run -dumpspec on (for example) a cross compiler targeting an embedded system, you will see the ...
C++ templates Turing-complete?
...;
template<int n>
struct State {
enum { value = n };
static char const * name;
};
template<int n>
char const* State<n>::name = "unnamed";
struct QAccept {
enum { value = -1 };
static char const* name;
};
struct QReject {
enum { value = -2 };
static char ...
How many and which are the uses of “const” in C++?
... compiler help you to decide when and when not you need to copy.
struct MyString {
char * getData() { /* copy: caller might write */ return mData; }
char const* getData() const { return mData; }
};
Explanation: You might want to share data when you copy something as long as the data of th...
How to check if a string in Python is in ASCII?
I want to I check whether a string is in ASCII or not.
16 Answers
16
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What is the meaning of the prefix N in T-SQL statements and when should I use it?
...
It's declaring the string as nvarchar data type, rather than varchar
You may have seen Transact-SQL code that passes strings around using
an N prefix. This denotes that the subsequent string is in Unicode
(the N actually stands for Nati...
Sending message through WhatsApp
...ntent(Intent.ACTION_SEND);
waIntent.setType("text/plain");
String text = "YOUR TEXT HERE";
PackageInfo info=pm.getPackageInfo("com.whatsapp", PackageManager.GET_META_DATA);
//Check if package exists or not. If not then code
//in catch block will be called
...
@try - catch block in Objective-C
...
All work perfectly :)
NSString *test = @"test";
unichar a;
int index = 5;
@try {
a = [test characterAtIndex:index];
}
@catch (NSException *exception) {
NSLog(@"%@", exception.reason);
NSLog(@"Char at index %d cannot be found", ...
When should one use final for method parameters and local variables?
...l variables when using conditions.
Let me give you an example:
final String name;
switch(pluginType) {
case CANDIDATE_EXPORT:
name = "Candidate Stuff";
break;
case JOB_POSTING_IMPORT:
name = "Blah";
break;
default:
...