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Macro vs Function in C
...uct webpage page;
page.numButtons = 2;
num_button_holes(page) -> 8
Finally, macros can be difficult to debug, producing weird syntax errors or runtime errors that you have to expand to understand (e.g. with gcc -E), because debuggers cannot step through macros, as in this example:
#define prin...
Polymorphism in C++
...ecific 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-specific code is made during compilation. A consequence of this: say...
How to check that an element is in a std::set?
... Note that using count() instead of find() is never better but potentially worse. This is because find() will return after the first match, count() will always iterate over all elements.
– Frerich Raabe
Nov 9 '09 at 15:50
...
How do I spool to a CSV formatted file using SQLPLUS?
...tion on IDs)
spool myfile.csv
select table_name, tablespace_name
from all_tables
where owner = 'SYS'
and tablespace_name is not null;
Output will be like:
TABLE_PRIVILEGE_MAP ,SYSTEM
SYSTEM_PRIVILEGE_MAP ,SYSTEM
...
How do I implement interfaces in python?
...interface, a module that is a part of the Zope Component Architecture, a really awesomely cool component framework. Here you don't subclass from the interfaces, but instead mark classes (or even instances) as implementing an interface. This can also be used to look up components from a component reg...
detach all packages while working in R
...*) is not necessary but can be useful to prevent the NULL reply from vertically spamming the R window.
(edit: 9/20/2019) In version 3.6.1
It may be helpful to convert loaded only names(sessionInfo()$loadedOnly) to explicitly attached packages first, and then detach the packages, as so.
lapply(names(...
How can I convert JSON to CSV?
...
First, your JSON has nested objects, so it normally cannot be directly converted to CSV. You need to change that to something like this:
{
"pk": 22,
"model": "auth.permission",
"codename": "add_logentry",
"content_type": 8,
"name": "Can add log entry"...
Get operating system info
...x]{2})', 'Windows');
// Doesn't seem like these are necessary...not totally sure though..
//$ros[] = array('(winnt)([0-9]{1,2}\.[0-9]{1,2}){0,1}', 'Windows NT');
//$ros[] = array('(windows nt)(([0-9]{1,2}\.[0-9]{1,2}){0,1})', 'Windows NT'); // fix by bg
$ros[] = array('Windows ME', '...
undefined reference to `WinMain@16'
...
Building without that semi-documented flag one would have to more specifically tell the linker which subsystem value one desires, and some Windows API import libraries will then in general have to be specified explicitly:
C:\test> gnuc x.cpp -Wl,-subsystem,windows
C:\test> objdump -x a.exe...
Why is there no xrange function in Python3?
...Some performance measurements, using timeit instead of trying to do it manually with time.
First, Apple 2.7.2 64-bit:
In [37]: %timeit collections.deque((x for x in xrange(10000000) if x%4 == 0), maxlen=0)
1 loops, best of 3: 1.05 s per loop
Now, python.org 3.3.0 64-bit:
In [83]: %timeit collec...