大约有 16,000 项符合查询结果（耗时：0.0311秒） [XML]
How do you effectively model inheritance in a database?
...s only the different elements.
So for example:
class Person {
public int ID;
public string FirstName;
public string LastName;
}
class Employee : Person {
public DateTime StartDate;
}
Would result in tables like:
table Person
------------
int id (PK)
string firstname
string last...
Is there a constraint that restricts my generic method to numeric types?
...Hejlsberg has described the reasons for not implementing the feature in an interview with Bruce Eckel:
And it's not clear that the added complexity is worth the small yield that you get. If something you want to do is not directly supported in the constraint system, you can do it with a factory ...
Is it possible to force Excel recognize UTF-8 CSV files automatically?
...
I use Notepad++ to easily convert the .csv from UTF-8 to UTF-8 with BOM
– Sébastien
Jun 6 '16 at 8:02
3
...
Best practices for circular shift (rotate) operations in C++
...apted it to rotate by the width of the type (using fixed-width types like uint32_t).
#include <stdint.h> // for uint32_t
#include <limits.h> // for CHAR_BIT
// #define NDEBUG
#include <assert.h>
static inline uint32_t rotl32 (uint32_t n, unsigned int c)
{
const unsigned int...
“Diff” an image using ImageMagick
... approach, particularly when comparing images which are mostly grayscale:
convert '(' file1.png -flatten -grayscale Rec709Luminance ')' \
'(' file2.png -flatten -grayscale Rec709Luminance ')' \
'(' -clone 0-1 -compose darken -composite ')' \
-channel RGB -combine diff.png
...
How can I initialize base class member variables in derived class constructor?
... B (or any subclass of A) to initialize them:
class A
{
protected:
A(int a, int b) : a(a), b(b) {} // Accessible to derived classes
// Change "protected" to "public" to allow others to instantiate A.
private:
int a, b; // Keep these variables private in A
};
class B : public A
{
publ...
Does Parallel.ForEach limit the number of active threads?
...of threads, but that number is calculated based on an algorithm that takes into account and appears to continually monitor the work done by the threads it's allocating to the ForEach. So if the body part of the ForEach calls out to long running IO-bound/blocking functions which would leave the threa...
Disable git EOL Conversions
...l files NOT found below
#
# These files are text and should be normalized (Convert crlf => lf)
*.css text
*.html text
*.java text
*.js text
*.json text
*.properties text
*.txt text
*.xml text
# These files are binary and shou...
Programmatically obtain the Android API level of a device?
...obtain API level programatically by the system constant (Build.VERSION.SDK_INT). For example you can run some piece of code which requires newer API in the following way (it will execute if the current device's API level is at least 4)
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.DONUT) {
}...
Can I call a constructor from another constructor (do constructor chaining) in C++?
... syntax is slightly different from C#:
class Foo {
public:
Foo(char x, int y) {}
Foo(int y) : Foo('a', y) {}
};
C++03: No
Unfortunately, there's no way to do this in C++03, but there are two ways of simulating this:
You can combine two (or more) constructors via default parameters:
class...