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App Inventor 2 “虚拟”屏幕：同一屏幕展示多屏内容，模拟切换屏幕 · App...
...虚拟屏幕（虚拟分屏）
好处：大部分需要连接的组件（比如蓝牙客户端、MQTT、BluetoothLE、Wifi、Socket等）如果跨屏幕的话，都需要重新连接，自行管理连接状态，非常不便利，且大部分场景并不是真正的需要多个屏幕...
The program can't start because libgcc_s_dw2-1.dll is missing
I have created a simple program in C++ with Code::Blocks.
16 Answers
16
...
How to avoid “if” chains?
...ltogether.
Option 1. You can't do this: use finally
Unfortunately, as a c++ developer, you can't do this. But this is the number one answer for languages that contain a finally keyword, since this is exactly what it is for.
try
{
if (!ok)
{
_log.Error("oops");
return;
...
Determine if map contains a value for a key?
...
Obviously you can write your own getValue() routine if you want (also in C++, there is no reason to use out), but I would suspect that once you get the hang of using std::map::find() you won't want to waste your time.
Also your code is slightly wrong:
m.find('2'); will search the map for a keyva...
Is there a SASS.js? Something like LESS.js?
... hasn't been updated in 2 years, I might interest you in sass.js. It's the C++ library libsass (also used by node-sass) compiled to JavaScript using Emscripten. An implementation to compile scss stylesheets linked or inlined in html can be found at sass.link.js.
Try out sass.js using the interactiv...
Python - Create a list with initial capacity
...3587.204933ms
doAllocate: 2701.154947ms
doGenerator: 1721.098185ms
While C++ gives (built with MSVC, 64-bit, Optimizations enabled)
Elements: 100000, Iterations: 144
doAppend: 74.0042ms
doReserve: 27.0015ms
doAllocate: 5.0003ms
C++ debug build produces:
Elements: 100000, Iterations: 144
doAppe...
Is there a difference between copy initialization and direct initialization?
...
C++17 Update
In C++17, the meaning of A_factory_func() changed from creating a temporary object (C++<=14) to just specifying the initialization of whatever object this expression is initialized to (loosely speaking) in C+...
Rolling median algorithm in C
...rc/Trunmed.c a few times as I wanted something similar too in a standalone C++ class / C subroutine. Note that this are actually two implementations in one, see src/library/stats/man/runmed.Rd (the source of the help file) which says
\details{
Apart from the end values, the result \code{y = runme...
How to initialize const member variable in a class?
...d into many translation units. However, to avoid complicated linker rules, C++ requires that every object has a unique definition. That rule would be broken if C++ allowed in-class definition of entities that needed to be stored in memory as objects.
A const variable has to be declared within the ...
Why cast unused return values to void?
...o ensure that where necessary error codes are always handled.
I think for C++ this is probably the only place that I prefer to use C-style casts too, since using the full static cast notation just feels like overkill here. Finally, if you're reviewing a coding standard or writing one, then it's al...