C++11 特性了解

Kernel Panic 总结了 C++11 中的 5 个实用特性：自动类型推导、强类型枚举、Unique 指针、static_assert、Lambdas 表达式。

Auto Type Deduction 自动类型推导

auto 关键字让用户得以使用 C++ 内置的类型推导特性。

Unique 指针

Unique 指针是 C++11 版本的智能指针类。

一旦你用 unique_ptr 关键字定义了一个对象，那么下列事件只要发生一个，对象就会被销毁并释放内存：

unique_ptr 管理的对象被销毁。

unique_ptr 管理的对象通过赋值操作符指向另一个指针，或调用了reset()方法。

#include "stdafx.h"

#include "TestCpp11.h"

#include <memory>

#include <vector>

#include <iostream>

#define MAX_LOADSTRING 100

// Global Variables:

HINSTANCE hInst; // current instance

TCHAR szTitle[MAX_LOADSTRING]; // The title bar text

TCHAR szWindowClass[MAX_LOADSTRING]; // the main window class name

// Forward declarations of functions included in this code module:

ATOM MyRegisterClass(HINSTANCE hInstance);

BOOL InitInstance(HINSTANCE, int);

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM);

class A

{

public:

A() :m_pStr(nullptr), m_num(0){ OutputDebugString(_T("A()\r\n")); };

A(UINT num) :m_pStr(nullptr),m_num(num){ OutputDebugString(_T("A()\r\n")); };

~A(){ OutputDebugString(_T("~A()\r\n")); };

UINT GetNum(){ return m_num; };

private:

TCHAR* m_pStr;

UINT m_num;

};

int APIENTRY _tWinMain(_In_ HINSTANCE hInstance,

_In_opt_ HINSTANCE hPrevInstance,

_In_ LPTSTR lpCmdLine,

_In_ int nCmdShow)

{

UNREFERENCED_PARAMETER(hPrevInstance);

UNREFERENCED_PARAMETER(lpCmdLine);

// TODO: Place code here.

MSG msg;

HACCEL hAccelTable;

// Initialize global strings

LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);

LoadString(hInstance, IDC_TESTCPP11, szWindowClass, MAX_LOADSTRING);

MyRegisterClass(hInstance);

// Perform application initialization:

if (!InitInstance (hInstance, SW_HIDE))

{

return FALSE;

}

hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_TESTCPP11));

{

std::unique_ptr<A> Smartptr(new A);

if (Smartptr->GetNum() == 0)

{

OutputDebugString(_T("Smartptr->GetNum() == 0\r\n"));

}

}



std::vector<A*> tVector;

A* pA1 = new A;

A* pA2 = new A(2);

A* pA3 = new A(4);

tVector.push_back(pA1);

tVector.push_back(pA2);

tVector.push_back(pA3);

//std::vector<A*>::iterator aitertor;

for (auto aitertor = tVector.begin(); aitertor != tVector.end(); aitertor++)

{

UINT i = (*aitertor)->GetNum();

std::cout << i << std::endl;

}

// Main message loop:

/*while (GetMessage(&msg, NULL, 0, 0))

{

if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))

{

TranslateMessage(&msg);

DispatchMessage(&msg);

}

}

*/

return (int) 0;

}

//

// FUNCTION: MyRegisterClass()

//

// PURPOSE: Registers the window class.

//

ATOM MyRegisterClass(HINSTANCE hInstance)

{

WNDCLASSEX wcex;

wcex.cbSize = sizeof(WNDCLASSEX);

wcex.style = CS_HREDRAW | CS_VREDRAW;

wcex.lpfnWndProc = WndProc;

wcex.cbClsExtra = 0;

wcex.cbWndExtra = 0;

wcex.hInstance = hInstance;

wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_TESTCPP11));

wcex.hCursor = LoadCursor(NULL, IDC_ARROW);

wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);

wcex.lpszMenuName = MAKEINTRESOURCE(IDC_TESTCPP11);

wcex.lpszClassName = szWindowClass;

wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

return RegisterClassEx(&wcex);

}

//

// FUNCTION: InitInstance(HINSTANCE, int)

//

// PURPOSE: Saves instance handle and creates main window

//

// COMMENTS:

//

// In this function, we save the instance handle in a global variable and

// create and display the main program window.

//

BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)

{

HWND hWnd;

hInst = hInstance; // Store instance handle in our global variable

hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,

CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

if (!hWnd)

{

return FALSE;

}

ShowWindow(hWnd, nCmdShow);

UpdateWindow(hWnd);

return TRUE;

}

//

// FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)

//

// PURPOSE: Processes messages for the main window.

//

// WM_COMMAND - process the application menu

// WM_PAINT - Paint the main window

// WM_DESTROY - post a quit message and return

//

//

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)

{

int wmId, wmEvent;

PAINTSTRUCT ps;

HDC hdc;

switch (message)

{

case WM_COMMAND:

wmId = LOWORD(wParam);

wmEvent = HIWORD(wParam);

// Parse the menu selections:

switch (wmId)

{

case IDM_ABOUT:

DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);

break;

case IDM_EXIT:

DestroyWindow(hWnd);

break;

default:

return DefWindowProc(hWnd, message, wParam, lParam);

}

break;

case WM_PAINT:

hdc = BeginPaint(hWnd, &ps);

// TODO: Add any drawing code here...

EndPaint(hWnd, &ps);

break;

case WM_DESTROY:

PostQuitMessage(0);

break;

default:

return DefWindowProc(hWnd, message, wParam, lParam);

}

return 0;

}

// Message handler for about box.

INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)

{

UNREFERENCED_PARAMETER(lParam);

switch (message)

{

case WM_INITDIALOG:

return (INT_PTR)TRUE;

case WM_COMMAND:

if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)

{

EndDialog(hDlg, LOWORD(wParam));

return (INT_PTR)TRUE;

}

break;

}

return (INT_PTR)FALSE;

}