C++ 笔记

1.  GDI+双缓冲绘图
DateTime t1 = DateTime.Now;
Bitmap bmp = new Bitmap(600, 600);
Graphics g = Graphics.FromImage(bmp);
if(flag)
{
brush = new LinearGradientBrush(new PointF(0.0f, 0.0f),
new PointF(700.0f, 300.0f), Color.Red, Color.Blue);
flag = false;
}
else
{
brush = new LinearGradientBrush(new PointF(0.0f, 0.0f),
new PointF(700.0f, 300.0f), Color.Blue, Color.Red);
flag = true;
}
for(int j = 0; j < 60; j ++)
{
for(int i = 0; i < 60; i++)
{
g.FillEllipse(brush, i * 10, j * 10, 10, 10);
}
}
this.CreateGraphics().DrawImage(bmp, 0, 0);
DateTime t2 = DateTime.Now;
TimeSpan sp = t2 - t1;
float per = 1000 / sp.Milliseconds;
this.label1.Text = "速度：" + per.ToString() + "帧/秒";

2.  绘制圆角矩形
BOOL yourClass::pathAddRoundRecangle(
            GraphicsPath *path ,
            RectF rect ,
            float roundSize )
{
 float left = rect.X;
 float top = rect.Y;
 float right = rect.Width + rect.X;
 float bottom = rect.Height + rect.Y;

 //如果取值不合法，指定roundSize为10或较短边的1/4
 if( roundSize <= 0 )
  roundSize = 10;
 float shortOne = rect.Width < rect.Height ? rect.Width : rect.Height;
 if( roundSize > shortOne / 4 )
  roundSize = shortOne / 4;

 //左上角
 path->AddArc( left , top , 2 * roundSize , 2 * roundSize , 180 , 90 );
 //上横线
 path->AddLine( left + roundSize , top , right - roundSize , top );
 //右上角
 path->AddArc( right - 2 * roundSize , top , 2 * roundSize , 2 * roundSize , 270 , 90 );
 //右竖线
 path->AddLine( right , top + roundSize , right , bottom - roundSize );
 //右下角
 path->AddArc( right - 2 * roundSize , bottom - 2 * roundSize , 2 * roundSize , 2 * roundSize , 0 , 90 );
 //下横线
 path->AddLine( left + roundSize , bottom , right - roundSize , bottom );
 //左下角
 path->AddArc( left , bottom - 2 * roundSize , 2 * roundSize , 2 * roundSize , 90 , 90 );
 //左竖线
 path->AddLine( left , top + roundSize , left , bottom - roundSize );
 return TRUE;
}

2.  网络

//取得本机名称
int CFileSendDlg::GetLocalHostName(CString &sHostName)
{
 char szHostName[256];
 int code;
 code = gethostname(szHostName, sizeof(szHostName));
 if(code != 0)
 {
  sHostName = "无法取得本机名称";
  return GetLastError();
 }
 sHostName = szHostName;
 return 0; 
}

//由计算机名取得本机IP地址
int CFileSendDlg::GetLocalIpByName(const CString &sHostName, CString &sIpAddress)
{
 struct hostent FAR * lpHostEnt=gethostbyname(sHostName);
 if(lpHostEnt==NULL)
 {
  //产生错误
  sIpAddress=_T("");
  return GetLastError();
 }
 //获取IP
 LPSTR lpAddr=lpHostEnt->h_addr_list[0];
 if(lpAddr)
 {
  struct in_addr inAddr;
  memmove(&inAddr,lpAddr,4);
  //转换为标准格式
  sIpAddress=inet_ntoa(inAddr);
  if(sIpAddress.IsEmpty())
   sIpAddress=_T("没有取得");
 }
 return 0;
}

int CFileSendDlg::GetNameByIp(const CString &IpAddress, CString &Name)
{
 unsigned long addr;
 addr=inet_addr(IpAddress);
 struct hostent FAR * lpHostEnt=gethostbyaddr((char *)&addr,4,AF_INET);
 if(lpHostEnt==NULL)
 {
  //产生错误
  Name=_T("");
  AfxMessageBox("无法获取计算机名");
  return -1;
 }
 CString name=lpHostEnt->h_name;
 Name=name;
 return 0;
}

int CServerSocket::Readn(char *bp, int len)
{
 int cnt;
 int rc; 
 
 cnt = len;
 while (cnt > 0)
 {
  rc = Receive(bp, cnt, 0);
  if (rc < 0)
   return -1;

  if (rc == 0)
   return len - cnt;

  bp += rc;
  cnt -= rc;
 }
 return len;
}

int CServerSocket::Writen(const char *bp, int len)
{
 int cnt;
 int rc;
 
 cnt = len;
 while (cnt > 0)
 {
  rc = Send(bp, cnt, 0);
  if (rc < 0)
   return -1;  

  if (rc == 0)
   return len - cnt;

  bp += rc;
  cnt -= rc;
 }
 return len;
}

if(inet_addr(servername)==INADDR_NONE)
{
    hp=gethostbyname(servername);
}
else {     addr=inet_addr(servername);     hp=gethostbyaddr((char*)&addr,sizeof(addr),AF_INET);
}
if(hp==NULL)
{
    closesocket(conn);
    return;
}

一段优秀代码
UINT  ServerThread(LPVOID pParam)
{	
    cout << "Starting up TCP server/r/n";

    //A SOCKET is simply a typedef for an unsigned int.
    //In Unix, socket handles were just about same as file 
    //handles which were again unsigned ints.
    //Since this cannot be entirely true under Windows
    //a new data type called SOCKET was defined.
    SOCKET server;

    //WSADATA is a struct that is filled up by the call 
    //to WSAStartup
    WSADATA wsaData;

    //The sockaddr_in specifies the address of the socket
    //for TCP/IP sockets. Other protocols use similar structures.
    sockaddr_in local;

    //WSAStartup initializes the program for calling WinSock.
    //The first parameter specifies the highest version of the 
    //WinSock specification, the program is allowed to use.
    int wsaret=WSAStartup(0x101,&wsaData);

    //WSAStartup returns zero on success.
    //If it fails we exit.
    if(wsaret!=0)
    {
        return 0;
    }

    //Now we populate the sockaddr_in structure
    local.sin_family=AF_INET; //Address family
    local.sin_addr.s_addr=INADDR_ANY; //Wild card IP address
    local.sin_port=htons((u_short)20248); //port to use

    //the socket function creates our SOCKET
    server=socket(AF_INET,SOCK_STREAM,0);

    //If the socket() function fails we exit
    if(server==INVALID_SOCKET)
    {
        return 0;
    }

    //bind links the socket we just created with the sockaddr_in 
    //structure. Basically it connects the socket with 
    //the local address and a specified port.
    //If it returns non-zero quit, as this indicates error
    if(bind(server,(sockaddr*)&local,sizeof(local))!=0)
    {
        return 0;
    }

    //listen instructs the socket to listen for incoming 
    //connections from clients. The second arg is the backlog
    if(listen(server,10)!=0)
    {
        return 0;
    }

    //we will need variables to hold the client socket.
    //thus we declare them here.
    SOCKET client;
    sockaddr_in from;
    int fromlen=sizeof(from);

    while(true)//we are looping endlessly
    {
        char temp[512];

        //accept() will accept an incoming
        //client connection
        client=accept(server,
            (struct sockaddr*)&from,&fromlen);
		
        sprintf(temp,"Your IP is %s/r/n",inet_ntoa(from.sin_addr));

        //we simply send this string to the client
        send(client,temp,strlen(temp),0);
        cout << "Connection from " << inet_ntoa(from.sin_addr) <<"/r/n";
		
        //close the client socket
        closesocket(client);

    }

    //closesocket() closes the socket and releases the socket descriptor
    closesocket(server);

    //originally this function probably had some use
    //currently this is just for backward compatibility
    //but it is safer to call it as I still believe some
    //implementations use this to terminate use of WS2_32.DLL 
    WSACleanup();

    return 0;
}

创建多级目录
/** 检查目录是否存在, 如果不存在, 则创建目录 */
#include <io.h>
#include <Mmsystem.h>
#pragma comment(lib, "winmm.lib")

BOOL CRecordSession::CreatePath(LPCTSTR lpszPathName)
{
	if (_access(lpszPathName, 0) != -1)
		return TRUE;

	typedef int (WINAPI *SHCREATEDIRECTORYEX)(HWND, LPCTSTR, SECURITY_ATTRIBUTES *);
	SHCREATEDIRECTORYEX SHCreateDirectoryEx = NULL;
	BOOL bCreated = FALSE;
	HMODULE hModule = LoadLibrary("shell32.dll");
	if (hModule)
	{
		SHCreateDirectoryEx = (SHCREATEDIRECTORYEX)GetProcAddress(hModule, "SHCreateDirectoryExA");
		if (SHCreateDirectoryEx)
			bCreated = (SHCreateDirectoryEx(NULL, lpszPathName, NULL) == ERROR_SUCCESS);
		FreeLibrary(hModule);
	}
	return bCreated;
}

/** 删除目录及文件 */
	CHAR   path[256] = "/0";
	::GetTempPath(256,path); 
	strcat(path, "emap");
	SHFILEOPSTRUCT ops;
	ZeroMemory(&ops, sizeof(ops));
	ops.wFunc = FO_DELETE;
	ops.pFrom = path;
	ops.fFlags = FOF_NOCONFIRMATION| FOF_NOERRORUI;
	DWORD dwErr = 0;
	TRY 
	{
		SetLastError(0);
		SHFileOperation(&ops);
	}
	CATCH_ALL(e)
	{	
		char buff[MAX_PATH];
		e->GetErrorMessage(buff, sizeof(buff));
		_snprintf(buff, sizeof(buff), "Delete Temp Path Failed: %s", buff);
		TRACE(buff);
	}
	END_CATCH_ALL