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C++虚继承的概念 - C/C++ - 清泛网 - 专注C/C++及内核技术
..."
8: #include <iostream>
9: using namespace std;
10:
11: //Base
12: class Base
13: {
14: public:
15: Base(){cout << "Base called..."<< endl;}
16: void print(){cout << "Base print..." <<endl;}
17: private:
18: };
19:
20: //Sub
21: class Sub //...
How do I get the base URL with PHP?
...
Fun 'base_url' snippet!
if (!function_exists('base_url')) {
function base_url($atRoot=FALSE, $atCore=FALSE, $parse=FALSE){
if (isset($_SERVER['HTTP_HOST'])) {
$http = isset($_SERVER['HTTPS']) && st...
Object-orientation in C
...be an instance of the superclass, and then you can cast around pointers to base and derived classes freely:
struct base
{
/* base class members */
};
struct derived
{
struct base super;
/* derived class members */
};
struct derived d;
struct base *base_ptr = (struct base *)&d; //...
C++ templates that accept only certain types
...
I suggest using Boost's static assert feature in concert with is_base_of from the Boost Type Traits library:
template<typename T>
class ObservableList {
BOOST_STATIC_ASSERT((is_base_of<List, T>::value)); //Yes, the double parentheses are needed, otherwise the comma will be...
Round to 5 (or other number) in Python
...ndard function in Python, but this works for me:
Python 2
def myround(x, base=5):
return int(base * round(float(x)/base))
Python3
def myround(x, base=5):
return base * round(x/base)
It is easy to see why the above works. You want to make sure that your number divided by 5 is an integ...
Algorithms based on number base systems? [closed]
I've noticed recently that there are a great many algorithms out there based in part or in whole on clever uses of numbers in creative bases. For example:
...
new keyword in method signature
...:
You cannot override a non-virtual or
static method. The overridden base
method must be virtual, abstract, or
override.
So the 'new' keyword is needed to allow you to 'override' non-virtual and static methods.
s...
Downcasting shared_ptr to shared_ptr?
...amic_pointer_cast. It is supported by std::shared_ptr.
std::shared_ptr<Base> base (new Derived());
std::shared_ptr<Derived> derived =
std::dynamic_pointer_cast<Derived> (base);
Documentation: https://en.cppreference.com/w/cpp/memory/shared_ptr/pointer_cast
Also, ...
How to use base class's constructors and assignment operator in C++?
...
You can explicitly call constructors and assignment operators:
class Base {
//...
public:
Base(const Base&) { /*...*/ }
Base& operator=(const Base&) { /*...*/ }
};
class Derived : public Base
{
int additional_;
public:
Derived(const Derived& d)
: Base(d...
What is the point of a private pure virtual function?
... classes. Methods of derived classes can't call virtual functions from the base class, but they can provide their own implementation for them. According to Herb Sutter, having public non-virtual interface in the base class and a private implementation that can be customized in the derived classes, a...