Question is related to C++ STL list::sort(Compare) where Compare is now a template.

I am looking for the correct syntax to override the list::sort(Compare) definition to work with list<pair<int, T> > definition.

//-The Compare Function

template<typename W>
bool weightsort(const pair<int, W> &node1, const pair<int, W> &node2)
{
    return (node1.second <= node2.second);
}


//- Abbreviated class definition containing  STL list definition and call to sort

template<typename T>
class Graph {
    ...
    vector<T> shortest_reach(int startId, T sigWeight) {
        ...
        list<pair<int, T> >                                       frontier;   //-Nodes currently on the Queue to be Explored.
        typename list<pair<int, T> >::iterator      fit;
        ...
            frontier.sort(weightsort);
        ...
    }
    ....
};


$ c++ program.cpp

error: no matching member function for call to 'sort'
            frontier.sort(weightsort);
            ~~~~~~~~~^~~~

usr/include/c++/v1/list:1059:14: note: candidate template ignored:
      couldn't infer template argument '_Comp'
        void sort(_Comp __comp);
             ^
/usr/include/c++/v1/list:1056:10: note: candidate function not viable:
      requires 0 arguments, but 1 was provided
    void sort();
         ^

What is the issue with the above code and how would you fix it?
indentation does not matter in this code, ":=" denotes the substitution, and "=" is the equal comparator.

========
Initial state of an array "a":

[[2, NULL, 2, NULL],
 [2, NULL, 2, NULL],
 [NULL, NULL, NULL, NULL],
 [NULL, NULL, NULL, NULL]]

========
Main function:

FUNCTION foo()
    FOR y := 0 to 3
        FOR x := 0 to 3
            IF a[x+1][y] != NULL
                IF a[x+1][y] = a[x][y]
                    a[x][y] := a[x][y]*2
                    a[x+1][y] := NULL
                END IF
                IF a[x][y] = NULL
                    a[x][y] := a[x+1][y]
                    a[x+1][y] := NULL
                END IF
            END IF
        END FOR
   END FOR
END FUNCTION


What does the foo function do?

How could you make foo more generic? Can we have three possible generalization directions ?

Hello , i've the following routine :

int Asio_Send_Pck(int iSendt,int Lsocket,char * Lbuff,int Len)

{

    LSession* iTempLSession = reinterpret_cast<LSession*>(Lsocket);

    boost::asio::async_write(iTempLSession->socket() ,

                              boost::asio::buffer(Lbuff, Len),

                              boost::bind(&LSession::handle_write, 

                              iTempLSession,

                              boost::asio::placeholders::error,

                              iTempLSession->data,

                              iSendt

                              ));

    return 0;

};

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But i always get an Invalid Arguments .

Here's my Lsession class :

class LSession
{
public:
  int readlen;
  int userdata;
  int deadtime;
  enum { max_length = 1024};
  char data_[max_length];
  
   LSession(boost::asio::io_service& io_service)
        : deadtime(0), socket_(io_service)
    {
        readlen = 0;
        userdata = 0;
    }

  ~LSession()
  {
	  socket_.close();
  }

  tcp::socket& socket()
  {
    return socket_;
  }

  void start()
  {	  
    socket_.async_read_some(boost::asio::buffer(data_, max_length),
        boost::bind(&LSession::handle_read, this,
          boost::asio::placeholders::error,
          boost::asio::placeholders::bytes_transferred));
  }

  void handle_read(const boost::system::error_code& error,
      size_t bytes_transferred)
  { 
    if (!error)
    {
	
	  try
	  {
	  if(Callback_readdata!= NULL)
	  

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…

Hello ;
I want to design a GUI.my application is as bellow :
while compiling my program , a first interface is displayed : it is for user authentication, by validating this step ,another interface is displayed :this interface is devided into two screen  show(Splitter with two column) the second interface is combined : a menu , and a tree view .by clicking in one item , a data and controls are shown in the right of interface.
To do this application , did I need for SDI or MDI
Also how to navigate between the two interfaces (the authentication interface and the second interface), should I use two Documents ?
For the first interface , I just want a simple area which display the logo of company and an edit control for tapping the Password. but since compiling the project ,always a classic dialog box is shown (made by Microsoft ).
Is there any idea which clarify my needs.
Kindly.

#include <iostream>
class A {
public:
    int ii = 20;
    A(int i = 200) {
        std::cout << "A() \n";
        ii = i;
    }
    A(const A& obj) {
        std::cout << "Copy Constructor\n";
    }
    A(A&& obj) noexcept {
        std::cout << "A(A&&)\n";
    }
};

void fun(A i) {
    std::cout << "Fun \n" << i.ii << std::endl;
}

int main(int argc, const char * argv[]) {
    fun(A(12)); // Why this is not calling move constructor.
    return 0;
}

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C++ add menu,
it seems ther is no problem but when the window is created the menu don't show on the screen.
do i need to add a redraw option ?

When i go the a other active window the menu is created. strains.

#include <windows.h>

void AddMenus(HWND);
HMENU hMenu;

int ID_Save;


const char g_szClassName[] = "myWindowClass";

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
        
        case WM_CREATE:
            AddMenus(hwnd);
            break;
        case WM_CLOSE:
            DestroyWindow(hwnd);
        break;
        case WM_DESTROY:
            PostQuitMessage(0);
        break;
        default:
        return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    
    
    return 0;
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,  LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG Msg;
   
    wc.cbSize        = sizeof(WNDCLASSEX);
    wc.style         = 0;
    wc.lpfnWndProc   = WndProc;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance     = hInstance;
    wc.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = g_szClassName;
    wc.hIconSm       = LoadIcon(NULL, IDI_APPLICATION);

    
    if(!RegisterClassEx(&wc))
    {
        MessageBox(NULL, "Window Registration Failed!", 

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…

In a CTreeCtrl, does GetChildItem() returns not null, if there is no child?  Is ItemHasChildren() is required? My below code hangs.

HTREEITEM FindTreeItem(HTREEITEM hItem, LPDISPATCH disp)
{
         if (disp == (LPDISPATCH)m_TreeCtrl.GetItemData(hItem))
            return hItem;

      HTREEITEM hChildItem = m_TreeCtrl.GetChildItem(hItem);
      while (hChildItem)
      {
            if (disp == (LPDISPATCH)m_TreeCtrl.GetItemData(hChildItem))
                  return hChildItem;

            HTREEITEM hItemFound = FindTreeItem(hChildItem, disp);
            if (hItemFound)
                  return hItemFound;

            hChildItem = m_TreeCtrl.GetNextItem(hChildItem, TVGN_NEXT);
      }

       return NULL;
}

Since VS 2013 in seems we can use VersionHelpers.h to allow us to ask which version of Windows we are running on.  I looks simple up thru Windows 7 -- but reading the documentation, once we get to Windows 8 or Windows 10, the doc starts talking about the need for a Manifest and mentions GUID.   Can somebody help me understand what is required to get this to work?   My goal: from a C++ program be able to detect if we are running on Windows 10 (or later).   Thanks.

Here is a question of C++ that I was practising on some other site. The code is given below. My code fails for multiple inputs. the output is only
clee olg  
 instead of
 clee olg
sho col
Given a string, S, of length N that is indexed from 0 to N-1, print its even-indexed and odd-indexed characters as space-separated strings on a single line.
INPUT-
The first line contains an integer, t (the number of test cases).
Each line  'i' of the subsequent lines contain a String,S
OUTPUT-
For each String S(where 0<= j<=N-1), print S's even-indexed characters, followed by a space, followed by S's odd-indexed characters.
.
Eg-
2
college
school
output-

clee olg
sho col

    
 int main() {
    int t;
    cin>>t;
    
    string str;
    vector<string>s_even;
    vector<string>s_odd;
    for(int i=0;i<t;i++)
    {
        getline(cin,str);
      
    for(int j=0;j<str.size();j++)
    {
        //s.push_back(str);
        if(j%2==0)
        { string  a;
         a=str[j];
            s_even.push_back(a);
            
        }
        else
        { string b;
         b= str[j];
            s_odd.push_back(b);
        }
    }
        
        
       copy(s_even.begin(),s_even.end(),ostream_iterator<string>(cout));
       
        cout<<" ";
       
        copy(s_odd.begin(),s_odd.end(),ostream_iterator<string>(cout));
        str.clear();
        s_odd.clear();
        s_even.clear();
        //cout<<endl;
    }
    return 0;
}       

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what is the best tool to do profiling for c++ multi threaded server daemon on Linux?

Complied program with -pg and the tried with gprof/gmon.out. Couldn't find call graph as per functions mentioned in my program. It has shown all low level api's call graph like string internals, memory allocations..etc.

Can someone suggest how to get call graph from gmon.out for multi threaded server daemon.

Any other tool(s)?

I have to support a Visual Studio 6 C++ file. I've extracted the code which has two projects. One is the code for a DLL and the other for a LIB file. In trying to compile as is, I get an error that says Link.exe couldn't load the LIB file.

Since c++ is not a language I've worked with before, what are the steps to compile. Is there a "make" process first? When I look at the dsp file, it says that it is not a valid file and to make and run.

I'm missing something pretty simple I'm sure. The program was written in the late 90's. I just want to convert it to Visual Studio 2010 or 2015.

I tried converting it to Visual Studio 10 but most of it is not translated. I've attached one .7z which contains two 7z project to expand into a c++ workspace.

Hi

I am a beginner to the arduino. To cut a long story short I have the code Serial.read which appears to read the 8 bit ascii value of a character.. This value is read into an int variable called Byte Received

Later in the code there is this
   

    if(ByteReceived == '1') // Single Quote! This is a character.
    {
      digitalWrite(led,HIGH);
      Serial.print(" LED ON ");
    }
    
    if(ByteReceived == '0')
    {
      digitalWrite(led,LOW);
      Serial.print(" LED OFF");
    }

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I do not understand the if statements e,g,

if(ByteReceived == '1')

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ByteReceived is an int and a value of 0 is null and a value of 1 is start of heading. Why are we comparing to 0 and 1 and why is it a character comparison ?

Furthermore I never get LED ON or LED OFF displayed but an led which is not pin 13 does flash .


Any help is much appreciated

Thanks

I wish to send a message to all client connected to my server application which uses an Indy 10 TCP Server component in Embarcadero C++ builder  XE 10.2 .

I have written the following function  which is meant to iterate through all the client connections to my server but it doesn't work.

I need some help in how to iterate through the list returned by the  IdTCPServer1->Contexts->LockList()  function.
I have seen an example in Delphi but my attempt in translating to C++ builder doesn't work.

void TForm1::BroadcastMessage(UnicodeString mess)
{
	TList *ls;
	int n;
	TIdContext *c;

	try
	{
		ls = IdTCPServer1->Contexts->LockList();
                n = ls->Count;
		for(int i=0;i<n;i++)
		{
			c = (TIdContext *)(ls->Items[i]); // <------ This line  is where the coding is wrong
			c->Connection->IOHandler->WriteLn(mess);
		}
		IdTCPServer1->Contexts->UnlockList();
	}
	catch(...)
	{
		IdTCPServer1->Contexts->UnlockList();
	}
}
//---------------------------------------------------------------------------

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