小编ger*_*nte的帖子

我在声明模板类型时遇到了很大困难,如下所示.

#include <cstdlib>
#include <iostream>

using namespace std;


template <class T>
class Foo
{
 typedef T Bar;
};

template <class T>
typedef typename Foo<T>::Bar Bar;




int main(int argc, char *argv[])
{

    Bar bar;

    Foo<int> foo;


    system("PAUSE");
    return EXIT_SUCCESS;
}

我收到错误

template declaration of `typedef typename Foo<T>::Bar Bar' 

关于线

template <class T>
typedef typename Foo<T>::Bar Bar;

我这样做是因为我想避免在我的代码中写入typename Foo :: Bar.

我究竟做错了什么？

我有一个带有SVG的网页.在某些形状上,我需要显示工具提示.但是,我无法将工具提示显示在它应该的位置,只是距离形状本身一些像素.

它出现在屏幕的右侧,可能距离大约300px.我用来获取坐标的代码如下:

d3.select("body")
  .select("svg")
  .select("g")
  .selectAll("circle")
  .on("mouseover", function(){return tooltip.style("visibility", "visible");})
  .on("mousemove", function(){

var svgPos = $('svg').offset(),

/*** Tooltip ***/

//This should be the correct one, but is displaying at all working at all.
/*x = svgPos.left + d3.event.target.cx.animVal.value,
y = svgPos.top + d3.event.target.cy.animVal.value;*/


//This displays a tool tip but way much to the left of the screen.
x = svgPos.left + d3.event.target.cx.animVal.value,
y = svgPos.top + d3.event.target.cy.animVal.value;

Tooltip
window.alert("svgPos: "+svgPos+"        top: "+y+"px          left: "+x+"px     "+d3.event.target.cx.animVal.value);


return tooltip.style("top", x+"px").style("left",y+"px");
})
.on("mouseout", …

我有一个客户端 - 服务器应用程序.

客户端使用两个不同的send()调用发送一个字符串,后跟一个整数.这两个数据应该存储在服务器上的两个不同变量中.

问题是发送的两个变量都是在recv()通话中接收的.因此,由两个不同的send()s 发送的两个字符串被链接并存储在第一个的缓冲区中recv().

server.c:

printf("Incoming connection from client %s:%i accepted\n",inet_ntoa(clientSocketAddress.sin_addr),ntohs(clientSocketAddress.sin_port));


memset(buffer,0,sizeof(buffer));
int sizeofMessage;
if ((recv(clientSocket,buffer,MAXBUFFERSIZE,0)==sizeofMessage)<0)
{
  printf("recv failed.");
  closesocket(serverSocket);
  clearWinsock();
  return EXIT_FAILURE;
}

char* Name=buffer;
printf("Name: %s\n",Name);

if ((recv(clientSocket,buffer,MAXBUFFERSIZE,0))<0)
{
  printf("bind failed.");

  closesocket(serverSocket);
  clearWinsock();
  return EXIT_FAILURE;
}

int integer=ntohs(atoi(buffer));
printf("integer: %i\n",intero);

client.c:

if (send(clientSocket,Name,strlen(Name),0)!=strlen(Name))
{
  printf("send failed");

  closesocket(clientSocket);
  clearWinsock();
  return EXIT_FAILURE;
}

printf("client send: %s",Name);

int age=35;
itoa(htons(age),buffer,10);
sizeofBuffer=strlen(buffer);
if (send(clientSocket,buffer,sizeofBuffer,0)!=sizeofBuffer)
{
  printf("bind failed.");

  closesocket(clientSocket);
  clearWinsock();
  return EXIT_FAILURE;
} …