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classes.cpp
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classes.cpp
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#include <string.h>
#include <utility>
#include <iostream>
#include <vector>
class Baz { // GOOD: polymorphic class suppresses copying
public:
Baz()=default;
Baz(const Baz&) = delete;
Baz& operator=(const Baz&) = delete;
virtual char get() { return 'B'; }
// ...
};
class Bar : public Baz {
public:
char get() override { return 'D'; }
// ...
};
void f(Baz& b) {
// auto b2 = b; // ok, compiler will detect inadvertent copying, and protest
}
class FooBase
{
public:
FooBase()=default;
FooBase(const FooBase&) = default;
FooBase(FooBase&&) = default;
FooBase& operator=(const FooBase&) = default;
FooBase& operator=(FooBase&&) = default;
virtual ~FooBase()=default;
};
class Foo : public FooBase
{
int n;
char* str;
public:
Foo()
{
str = new char[1000000];
}
~Foo()
{
std::cout << "~Foo" << std::endl;
delete [] str;
}
Foo(const Foo& other) // copy constructor
{
strncpy(str, other.str, 100);
}
Foo(Foo&& other) noexcept // move constructor
: str(std::exchange(other.str, nullptr))
{
}
Foo& operator=(const Foo& other) // copy assignment
{
return *this = Foo(other);
}
Foo& operator=(Foo&& other) noexcept // move assignment
{
std::swap(str, other.str);
return *this;
}
};
int main() {
Bar xbar;
f(xbar);
std::cout << xbar.get() << std::endl;
Baz xbaz;
std::cout << xbaz.get() << std::endl;
Foo* x = new Foo();
delete x;
return 0;
}