I implemented a simple C++ binary serialization framework that makes a structure or class serializable by adding a macro that usually takes one line of code as shown in the example below:
struct A
{
bool x;
int y;
AWL_SERIALIZABLE(x, y)
};
There is also a macro that makes a structure or a class equatable:
AWL_MEMBERWISE_EQUATABLE(A)
The code below demonstrates how to parse GUID in C++ using a regular expression:
#include <iostream>
#include <string>
#include <regex>
int main()
{
static const std::wregex regex(L"[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}");
std::wstring sample = L"850fe1da-0ea6-c1a8-9810-0c1cece30698";
std::match_results<std::wstring::const_iterator> match;
if (std::regex_match(sample, match, regex))
{
std::wcout << L"matches" << std::endl;
}
else
{
std::wcout << L"does not match" << std::endl;
}
return 0;
}
For example, std::forward comes to play if I implement a template container with two ‘insert‘ function overloads that take the parameters of type const T & and T && respectively. I implement all the private insertion logic with T&&, but when I need to know the original value type passed to ‘insert‘ method I use std::forward as shown in the example below:
#include <iostream>
#include <string>
class Value
{
public:
Value(const char * sz) : m_s(sz)
{
}
Value(const Value & other) : m_s(other.m_s)
{
std::cout << "copy constructor: " << m_s << std::endl;
}
Value(Value && other) : m_s(std::move(other.m_s))
{
std::cout << "move constructor: " << m_s << std::endl;
}
const std::string & ToString() const
{
return m_s;
}
private:
std::string m_s;
};
The string representation of a type is implementation defined in C++, for example the following code produce the different output with MSVC, GCC and CLang:
#include <string>
#include <iostream>
struct A {};
class B {};
namespace ns
{
struct X {};
}
int main()
{
std::cout << typeid(A).name() << ", " << typeid(B).name() << ", " << typeid(ns::X).name() << ", " << typeid(std::string).name() << std::endl;
return 0;
}
We had a discussion with colleagues on why in the following code we cannot simply use
static_assert(false)
but need to do a trick with ‘always_false’:
#include <type_traits>
template<typename>
struct always_false : std::false_type {};
template<typename Type>
constexpr int Get()
{
if constexpr (std::is_same_v<Type, int>)
{
return 1;
}
else if constexpr (std::is_same_v<Type, bool>)
{
return 2;
}
else {
static_assert(always_false<Type>::value);
}
}
The original S57 map consists of the following layers:
ogrinfo E:\temp\ENC_ROOT\US4CA11M\US4CA11M.000
INFO: Open of `E:\temp\ENC_ROOT\US4CA11M\US4CA11M.000'
using driver `S57' successful.
1: DSID (None)
2: Point (Point)
3: Line (Line String)
4: Area (Polygon)
5: Meta (None)
So I was able to convert each layer separately one by one without errors:
ogr2ogr -f GeoJSON US1HA02M-Area.json E:\temp\ENC_ROOT\US1HA02M\US1HA02M.000 Area -lco RFC7946=YES -skipfailures ogr2ogr -f GeoJSON US1HA02M-Point.json E:\temp\ENC_ROOT\US1HA02M\US1HA02M.000 Point -lco RFC7946=YES -skipfailures ogr2ogr -f GeoJSON US1HA02M-Line.json E:\temp\ENC_ROOT\US1HA02M\US1HA02M.000 Line -lco RFC7946=YES -skipfailures ogr2ogr -f GeoJSON US1HA02M-DSID.json E:\temp\ENC_ROOT\US1HA02M\US1HA02M.000 DSID -lco RFC7946=YES -skipfailures Warning 1: No SRS set on layer. Assuming it is long/lat on WGS84 ellipsoid ogr2ogr -f GeoJSON US1HA02M-Meta.json E:\temp\ENC_ROOT\US1HA02M\US1HA02M.000 Meta -lco RFC7946=YES -skipfailures Warning 1: No SRS set on layer. Assuming it is long/lat on WGS84 ellipsoid
I installed Node.js and Vue.js cli with the following commands
npm install -g @vue/cli npm install -g @vue/cli-init
and a sample application with
vue init webpack-simple my-vue-app cd my-vue-app npm install npm run dev
Below I wrote down a simple PHP script that saves client IP address to a file. If the IP address of your home machine periodically changes, you can store it on a web server once a minute by scheduling a task like this:
sudo crontab -u <user> -e
* * * * * wget -q -O /dev/null -o /dev/null "https://yourwebsite.com/ip.php?rig=rig1&password=XXXXX"
where ip.php is the following PHP script:
(more…)
WIX bootstrapper application (BA) can easily determine if it runs as admin with the following code:
using System;
using System.Diagnostics;
using System.Security.Principal;
static bool IsAdmin()
{
WindowsIdentity id = WindowsIdentity.GetCurrent();
WindowsPrincipal principal = new WindowsPrincipal(id);
return principal.IsInRole(WindowsBuiltInRole.Administrator);
}
and if it does not, run a new instance as admin and exit:
static void RunAsAdmin()
{
ProcessStartInfo proc = new ProcessStartInfo
{
UseShellExecute = true,
WorkingDirectory = Environment.CurrentDirectory,
FileName = Process.GetCurrentProcess().MainModule.FileName,
Verb = "runas"
};
Process.Start(proc);
}
Once std::vector is filled (size() equals to capacity()), a subsequent push_back(…) results in an exponential expansion of the vector capacity. The following table shows that the expansion happens when the index reaches a power of two:
index: 0, capacity: 1, address: 0x1fa6c20 index: 1, capacity: 2, address: 0x1fa6c40 index: 2, capacity: 4, address: 0x1fa6c20 index: 4, capacity: 8, address: 0x1fa6c60 index: 8, capacity: 16, address: 0x1fa6c90 index: 16, capacity: 32, address: 0x1fa6ce0 index: 32, capacity: 64, address: 0x1fa6d70 index: 64, capacity: 128, address: 0x1fa6e80 index: 128, capacity: 256, address: 0x1fa7090 index: 256, capacity: 512, address: 0x1fa74a0 index: 512, capacity: 1024, address: 0x1fa7cb0 index: 1024, capacity: 2048, address: 0x1fa8cc0 index: 2048, capacity: 4096, address: 0x1faacd0 index: 4096, capacity: 8192, address: 0x1faece0 index: 8192, capacity: 16384, address: 0x1fb6cf0 index: 16384, capacity: 32768, address: 0x1fc6d00 index: 32768, capacity: 65536, address: 0x1fe6d10 index: 65536, capacity: 131072, address: 0x2026d20 index: 131072, capacity: 262144, address: 0x20a6d30 index: 262144, capacity: 524288, address: 0x21a6d40 index: 524288, capacity: 1048576, address: 0x23a6d50 index: 1048576, capacity: 2097152, address: 0x27a6d60 index: 2097152, capacity: 4194304, address: 0x2fa6d70 index: 4194304, capacity: 8388608, address: 0x7f8e9225f010 index: 8388608, capacity: 16777216, address: 0x7f8e8e25e010 index: 16777216, capacity: 33554432, address: 0x7f8e8625d010 index: 33554432, capacity: 67108864, address: 0x7f8e7625c010 index: 67108864, capacity: 134217728, address: 0x7f8e5625b010 index: 134217728, capacity: 268435456, address: 0x7f8e1625a010 index: 268435456, capacity: 536870912, address: 0x7f8d96259010 index: 536870912, capacity: 1073741824, address: 0x7f8c96258010
