welcome to modern c++
TRANSCRIPT
WareValleyhttp://www.warevalley.com
Overviewvector<vector<int>>
user-defined
literals thread_local
=default, =deleteatomic<T> auto f() -> int
array<T, N>
decltypevector<LocalType>
noexceptregex
initializer lists
constexpr
extern template
unordered_map<int, string>raw string literals
nullptr auto i = v.begin();
async
lambdas
[]{ foo(); }
template
aliases
unique_ptr<T>
shared_ptr<T>
weak_ptr<T>
thread, mutex
for (x : coll)
override,
final
variadic templatestemplate <typename T…>
function<>
promise<T>/future<T>
tuple<int, float, string>strongly-typed enums
enum class E {…};
static_assert(x)
rvalue references(move semantics)
delegating constructors
packaged_task<T>
Decucing Type
Concurrency
Performance
Smart Pointer
lambda expression
range-based for
initializer list
…
auto f() -> int
decltype
auto i = v.begin();
decltype(auto)
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• 경우 1 : ParamType이 pointer 또는 reference 타입이지만,
universal reference 타입은 아닌 경우 (L-Value 및 R-Value와 다름)
• 경우 2 : ParamType이 universal reference 타입인 경우
• 경우 3 : ParamType이 pointer 또는 reference 타입이 아닌 경우
* 자세한 설명: http://devluna.blogspot.kr/2015/02/item-1-understand-template-type.html
5
int i = 10;double d = 3.14;
auto i = 10;auto d = 3.14;
C++98 C++11
• 자세한 설명: http://devluna.blogspot.kr/2015/02/item-2-understand-auto-type-deduction.html
6
C++98
C++11
for (std::vector<std::tuple<std::string, int, double>>::iterator IT = vtList.begin();IT != vtList.end(); IT++)
{…
}
for (auto IT = vtList.begin(); IT != vtList.end(); IT++){
…}
std::vector<std::tuple<std::string, int, double>> vtList;
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int i = 10;decltype(i) j = 10; // intconst int i2 = 0; // decltype(i2) 는 const intbool f(const Widget& w); // decltype(w)는 const Widget&
// decltype(f)는 bool(const Widget&)
• 자세한 설명: http://devluna.blogspot.kr/2015/02/item-3-understand-decltype.html
8
template<typename Container, typename Index>decltype(auto) authAndAccess(Container& c, Index i){
authenticateUser();return c[i];
}
=default, =delete
initializer lists nullptr
for (x : coll)
override,
final
strongly-typed enumsenum class E {…};
aliases
11
int arr[] = { 1, 2, 3, 4, 5 };
for (int i = 0; i < 5; ++i)std::cout << arr[i] << std::endl;
int arr[] = { 1, 2, 3, 4, 5 };
for (auto& i : arr)std::cout << i << std::endl;
C++98 C++11
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void f(int) void f(bool);
void f(void*);
f(0); // f(int)f(NULL); // f(int)f(nullptr); // f(void*)
• 자세한 설명: http://devluna.blogspot.kr/2015/04/item-08-0-null-nullptr-mva-version.html
13
template<typename FuncType, typename MuxType, typename PtrType>decltype(auto) lockAndCall (FuncType func, MuxType & mutex, PtrType ptr){
MuxGuard g(mutex);return func(ptr);
}
auto result1 = lockAndCall(f1, f1m, 0); // error!...auto result2 = lockAndCall(f2, f2m, NULL); // error!...auto result3 = lockAndCall(f3, f3m, nullptr); // fine
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// C++98typedef std::unique_ptr<std::unordered_map<std::string, std::string>> UptrMapSS;
// C++11using UPtrMapSS = std::unique_ptr<std::unordered_map<std::string, std::string>>;
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template<typename T>struct MyAlloList{
typedef std::list<T,myalloc<T>> type;};
MyAllocList<Widget>::type lw;
template<typename T>class Widget {private:
typename MyAllocList<T>::type list;};
C++98template<typename T>using MyAllocList = std::list<T, MyAlloc<T>>;
MyAllocList<Widget> lw;
template<typename T>class Widget {private:
MyAllocList<T> list;};
C++11
• 자세한 설명: http://devluna.blogspot.kr/2015/03/item-9-typedef.html
16
enum Color { black, white, red, blue };
Color a = black;if (a < 14.5) { … } // OK
enum Feelings { excited, moody, blue }; // error
enum class Color { black, white, red, blue };
Color a = black; // errorColor b = Color::black; // OK if(b < 14.5) { … } // error
enum class Feelings { excited, moody, blue }; // OK
• 자세한 설명: http://devluna.blogspot.kr/2015/03/item-10-scoped-enum.html
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class Widget {...private:
Widget(const Widget&);Widget& operator = (const Widget&);
}
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class Widget {...
Widget(const Widget&) = delete;Widget& operator = (const Widget&) = delete;
}
bool isLucky(int number);
if (isLucky(‘a’)) ... // ‘a’(char) -> 97(int)if (isLucky(true)) ... // true(bool) -> 1(int)if (isLucky(3.5)) ... // 3.5(double) -> 3(int)
bool isLucky(int number);bool isLucky(char) = delete;
if (isLucky(‘a’)) ... // errorif (isLucky(true)) ... // true(bool) -> 1(int)if (isLucky(3.5)) ... // 3.5(double) -> 3(int)
• 자세한 설명: http://devluna.blogspot.kr/2015/03/item-11-private-delete.html
19 • 자세한 설명: http://devluna.blogspot.kr/2015/04/item-17-special.html
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class Base {public:
virtual void mf1() const;virtual void mf2(int x);virtual void mf3() &;void mf4() const;
};
class Derived : public Base {public:
virtual void mf1();virtual void mf2(unsigned int x);virtual void mf3() &&;void mf4() const;
};
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class Base {public:
virtual void mf1() const;virtual void mf2(int x);virtual void mf3() &;virtual void mf4() const;
};
class Derived : public Base {public:
virtual void mf1() override;virtual void mf2(unsigned int x) override;virtual void mf3() && override;void mf4() const override;
};
class Derived : public Base {public:
virtual void mf1() const override;virtual void mf2(int x) override;virtual void mf3() & override;void mf4() const override;
};
• 자세한 설명: http://devluna.blogspot.kr/2015/04/item-11-override.html
22
Object 초기화할때아래와같이할수있다.
int x(0); // initializer is in parentheses
int y = 0; // initializer follows "="
int z{0}; // initializer is in braces
int z = { 0 }; // initializer is in braces
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non-static value에대한
default 초기값을설정하는데
( )는안된다.
class Widget
{
private:
int x{0}; // fine. x's default value is 0
int y = 0; // also fine
int z(0); // error!
};
std::atomic<int> ai1{0}; // fine
std::atomic<int> ai2(0); // fine
std::atomic<int> ai3 = 0; // error!
copy가안되는 object에대해서는
()는되는데, =는안된다.
둘다가능한건 { } 뿐이다.
- 모든상황에다사용이가능하다.
+ 기존에불가능했던것을쉽게사용할수있게해주었다.
std::vector<int> v{ 1, 3, 5 }; // v's initial content is 1, 3, 5
• 자세한 설명: http://devluna.blogspot.kr/2015/04/item-07-uniform-initializer.html
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{ }를이용한생성자는가능한무조건 std::initializer_list 생성자를호출한다.
(더적합한생성자가있음에도불구하고…)
class Widget
{
public:
Widget(int i, bool b);
Widget(int i, double d);
Widget(std::initializer_list<long double> il);
...
};
Widget w2{ 10, true }; // 10 and true convert to long double
Widget w4{ 10, 5.0 }; // 10 and 5.0 convert to long double
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Narrowing conversion 방지
class Widget {
public:
Widget(std::initializer_list<bool> il);
...
};
Widget w{10, 5.0}; // error! invalid narrowing conversion from 'double' to 'bool'
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Most vexing parse 방지
class Widget {
public:
Widget();
Widget(std::initializer_list<int> il);
...
};
Widget w1; // calls default ctor
Widget w2{}; // also calls default ctor
Widget w3(); // most vexing parse! declares a function!
http://devluna.blogspot.kr/2015/01/item-6-c-most-vexing-parse.html