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Fast way of counting non-zero bits in positive integer
...p://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetTable
POPCOUNT_TABLE16 = [0] * 2**16
for index in range(len(POPCOUNT_TABLE16)):
POPCOUNT_TABLE16[index] = (index & 1) + POPCOUNT_TABLE16[index >> 1]
def popcount32_table16(v):
return (POPCOUNT_TABLE16[ v & 0xf...
Why use static_cast(x) instead of (int)x?
I've heard that the static_cast function should be preferred to C-style or simple function-style casting. Is this true? Why?
...
What is the most efficient Java Collections library? [closed]
... long mem = usedMem();
TIntIntHashMap ours = new TIntIntHashMap(SET_SIZE);
for ( int i = dataset.size(); i-- > 0; ) {
ours.put(i, i);
}
mem = usedMem() - mem;
System.err.println("trove " + mem + " bytes");
ours.clear();
}
publi...
How do I delete an exported environment variable?
Before installing gnuplot, I set the environment variable GNUPLOT_DRIVER_DIR = /home/gnuplot/build/src . During the installation, something went wrong.
...
“open/close” SqlConnection or keep open?
...ion()) {} public SqlConnection GetConnection() { return new SqlConnection(_connectionString); }
– ganders
Jan 23 at 17:12
...
Returning an array using C
...ype; the function actually receives a pointer type:
void foo(char *a, size_t asize)
{
// do something with a
}
int bar(void)
{
char str[6] = "Hello";
foo(str, sizeof str);
}
In the call to foo, the expression str is converted from type char [6] to char *, which is why the first parameter o...
Give all the permissions to a user on a DB
...user needs access to the database, obviously:
GRANT CONNECT ON DATABASE my_db TO my_user;
And (at least) the USAGE privilege on the schema:
GRANT USAGE ON SCHEMA public TO my_user;
Or grant USAGE on all custom schemas:
DO
$$
BEGIN
-- RAISE NOTICE '%', ( -- use instead of EXECUTE to see ge...
What's the difference between Perl's backticks, system, and exec?
...t, and don't want to wait for it to return. system is really just
sub my_system {
die "could not fork\n" unless defined(my $pid = fork);
return waitpid $pid, 0 if $pid; #parent waits for child
exec @_; #replace child with new process
}
You may also want to read the waitpid and perli...
What are the differences between Deferred, Promise and Future in JavaScript?
...es from [Functional Reactive Programming|haskell.org/haskellwiki/Functional_Reactive_Programming], which is a technique for flattening callbacks."
– fncomp
Feb 11 '13 at 5:32
2
...
Integrate ZXing in Android Studio
...tIntegrator(this);
integrator.setDesiredBarcodeFormats(IntentIntegrator.ONE_D_CODE_TYPES);
integrator.setPrompt("Scan a barcode");
integrator.setCameraId(0); // Use a specific camera of the device
integrator.setBeepEnabled(false);
integrator.setBarcodeImageEnabled(true);
integrator.initiateScan();
...