Ref: https://goodliffe.blogspot.com/2011/07/c-declaring-pointer-to-template-method.html
Seems like others don't have the issues I am encoutering with this blog, but I have been unable to build/run case 5. I added this simple main() function:

int main()
{
	PointerToNormalMemberFunction(); // target 1
	PointerToTemplateMemberFunction(); // target 2
	PointerToTemplateMemberFunctionWithTwoParameters(); // terget 3
	PointerToTemplateMemberInTemplateClass(); // target 4
//	HoldingAPointerToTemplateMemberInTemplateClass(); // target 5 ---> Had to comment this out
}

Select all Open in new window

In the referenced link are five cases. I am having trouble with case 5. Here is the code for this last case. Can you get a simple test program to work with this case 5? Thanks!

#pragma once

#include <iostream>

template<typename TYPE>
class Target5
{
public:
	Target5(const TYPE &value) : value(value) {}
	TYPE value;

	template <typename T>
	void OneParam(T a)
	{
		std::cout << "Target5::OneParam(" << value << "," << a << ")\n";

		typedef void (Target5<E>::*MethodTypeToCall)(T);
		// Here, the compiler picks the right overload
		MethodTypeToCall toCall = &Target5<E>::Private;
		// In this case, the compiler does not let us write the following line (parse error):
		//MethodTypeToCall toCall = &Target5<E>::Private<t;;
		(this->*toCall)(a);
	}

	template <typename T1, typename T2>
	void TwoParam(T1 a, T2 b)
	{
		std::cout << "Target5::TwoParam(" << value << "," << a << "," << b << ")\n";

		typedef 

Select all Open in new window

…

Problem with visual 6 C++ code converting to visual studio 2010 c++. The following is the only code that errors out. The rest of the lib converts and compiles fine if I remark out this one line of code.

      WCHAR *printable = new WCHAR[(dwBufferSize+1)*2];
      printable[0] = '\0';

      for (unsigned long i =0;i<dwBufferSize;i++)
      {
         WCHAR scratch[3];
		 wsprintf(scratch,L"%02X", pBuffer[i]);   //This is the problem code. wsprintf requires LPSTR but scratch is WCHAR
         wcscat(printable, scratch);
      }

      *pbstrEncrypted = SysAllocStringLen(printable, dwBufferSize*2);

I've looked for code on the internet to convert a variable from WCHAR to LPSTR and back again. I could make do with that.  As near as I can see the wsprintf with the format 
code %02X takes a single wide char and makes it two hex output characters and concatenates it to the printable variable. This code was written in 2000.

Bob


      delete [] printable;

Select all Open in new window

With Lilypad e-textiles do you have to pair an Arduino board (nano or uno) with it or are these programmable themselves with Arduino software.  I have multiple LilyPad Arduino Simple Snaps and would like to program them to allow a student to push a button and have led lights go off in succession.
We are attempting to make interactive maps like what you would see in a museum.  Button goes off and the lights light up an army path or the outline of a state.

I am using zlib 1.2.7 zlibstat.lib with a Visual Studio 2015 MFC application. When I include this library I get warning messages:

zlibstatic.lib(gzlib.obj) : warning LNK4049: locally defined symbol __stdio_common_vsprintf imported
zlibstatic.lib(gzwrite.obj) : warning LNK4049: locally defined symbol __stdio_common_vsprintf imported
zlibstatic.lib(gzlib.obj) : warning LNK4049: locally defined symbol free imported
zlibstatic.lib(gzwrite.obj) : warning LNK4049: locally defined symbol free imported
zlibstatic.lib(zutil.obj) : warning LNK4049: locally defined symbol free imported
zlibstatic.lib(gzlib.obj) : warning LNK4049: locally defined symbol malloc imported
zlibstatic.lib(gzwrite.obj) : warning LNK4049: locally defined symbol malloc imported
zlibstatic.lib(zutil.obj) : warning LNK4049: locally defined symbol malloc imported
zlibstatic.lib(gzlib.obj) : warning LNK4049: locally defined symbol wcstombs imported
zlibstatic.lib(gzlib.obj) : warning LNK4049: locally defined symbol _wopen imported
zlibstatic.lib(gzlib.obj) : warning LNK4049: locally defined symbol _lseeki64 imported
zlibstatic.lib(gzlib.obj) : warning LNK4049: locally defined symbol open imported
OLDNAMES.lib(open.obi) : warning LNK4049: locally defined symbol open imported
zlibstatic.lib(gzwrite.obj) : warning LNK4049: locally defined symbol _errno imported
zlibstatic.lib(gzwrite.obj) : warning LNK4049: locally defined symbol strerror imported
zlibstatic.lib(gzwrite.obj) : warning LNK4049: locally…

I'm trying to run a very simple Hello World program on a Linux workstation.  The code compiles, but when I double-click on the .exe file to run it, a window pops up with the message "An Error Occurred While Loading the Archive".  

I've attached the code and Makefile below.

What am I doing wrong?

Thanks!

#include <iostream>
using namespace std;
//hello.cpp

int main()
{
  cout << 'Hello world!\n';
  return 0;
}

Select all Open in new window

TARGET	= hello.exe
OBJECT_01	= hello.o
SOURCE_01	= hello.cpp

$(TARGET): $(OBJECT_01)
	gcc -o $(TARGET) $(OBJECT_01) -lstdc++

$(OBJECT_01): $(SOURCE_01)
	gcc -c $(SOURCE_01) -o $(OBJECT_01)

all: $(TARGET)

clean:
	-rm -f $(TARGET) 
	-rm -f $(OBJECT_01)

Select all Open in new window

Hi,
I am facing an issue regarding unicode text.
In a ATL dll project I am using LDAP to get data from Active Directory. Following is the sample code.  

IDirectorySearch *pDSSearch;
ADS_SEARCH_COLUMN col;
hr = pDSSearch->SetSearchPreference(rgSearchPrefs, ARRAYSIZE(rgSearchPrefs));
hr = pDSSearch->ExecuteSearch(strFilter, pszAttr ,dwAttrNameSize, &hSearch );

if(SUCCEEDED(hr))
	{						
		switch(col.dwADsType)
		{ 
			case  ADSTYPE_DN_STRING:
			case ADSTYPE_CASE_IGNORE_STRING:
				{			
					for(size_t x=0; x<col.dwNumValues;x++)
					{
						CString name = col.pADsValues[x].CaseIgnoreString; //fails for unicode text
					}
				}
		}
	}

Select all Open in new window

The line CString name = col.pADsValues[x].CaseIgnoreString; works fine for English text, but returns '???' for other languages. For example if the Active directory contains any user's name in Chinese or Japanese text '邮箱' then CString name shows '???' instead of the actual unicode text.
The same code works properly in another MFC Application project but fails for this ATL dll project.

Project settings are :
Configuration Type : Dynamic Library(.dll)
Use of MFC :      Use MFC in a Static Library
Use of ATL :       Static Link to ATL
Character Set :  Use Unicode Character Set

Cannot trace what I have been missing out. Please help.

Code returning error message.  Unsure how to fix.

exit status 1
main.cpp:19:1: error: expected unqualified-id before '{' token
 {


Here's the code:

#include <iostream>
#include <iomanip>
using namespace std;
const int arrsize = 9;
int main()
{
int i = 0;
int j = 0;
int matrix[3][3];
cout<<" please enter 9 digits "<<endl;
for (int i = 0; i < 3; i++)
{
  for (int j = 0; j < 3; j++)
  {
    cin>>matrix[i][j];
  }
}
}
{
for (int i = 0; i < 3; i++)
{
  for (int j = 0; j < 3; j++)
  {
    cout>>matrix[i][j];
  }
  cout<<endl;
}
}

Hi I have a 2D vector in a library which gets populated with different types of data this part is working fine now I need to pass the 2D vector back to my main app from a function call but this function call is failing

Here is the structure that makes up the vector in the library and how I am trying to call the data in the vector from a function:

//Library code
typedef struct _DEVICEDETAILS
{
	std::string IPaddr;
	int HTTPPort;
	int HTTPSPort;
	int RTPSPort;
	std::string Model;
	std::string Name;
	std::string token;
	std::vector<std::string> RSTPURL;
	std::vector<char*> data;
	std::vector<size_t> datalen;
	std::string _mediaXaddr;
	int Encoding;
	int Width;
	int Height;
	int Quality;
	int FrameRateLimit;
	int EncodingInterval;
	int Bitrate;

}DEVICEDETAILS;

struct ONVIFDEVICE
{
	std::string MacAddr;
	std::vector<DEVICEDETAILS> _videotype;
};

ONVIFDEVICE m_MacAddr;
std::vector<std::vector<ONVIFDEVICE>> v_Device;

void GetOvifInfo(std::vector<std::vector<ONVIFDEVICE>> &returnInfo)
{
  other code .......
   int m_size =v_Device.size();
   v_Device.resize(m_size+1);
   v_Device[nFindDev].push_back(m_Mac); // info gets populated into each element here
   nFindDev++;
   
  //Need to do a deep copy from vector v_Device to  vector returnInfo

}

// Main App code
typedef struct _mDEVICEDETAILS
{
	std::string IPaddr;
	int HTTPPort;
	int HTTPSPort;
	int RTPSPort;
	std::string Model;
	std::string Name;
	std::string token;
	std::vector<std::string> RSTPURL;
	std::vector<char*>

Select all Open in new window

…

I am implementing a draggable window and in my mousemove i am setting it's position using MoveWindow() API but problem is while it is moving it is leaving its trace behind i have attached the image The place where it was present earlier is not getting erased, i have used OnEraseBackground to true and false

Hey!

I am developing an application using JetBrains CLion 2018.2.4 with cmake 3.12.2 and Visual Studio 2017 compiler.
Let me set up things first.

Here is the base class:

class Header
{
public:
   enum MessageType
   {
      Message = 100,
      Command = 101,
      InvalidMessage = 102
   };

   Header();
   Header(Header::MessageType messageType);
   virtual ~Header() = default;

   Header::MessageType GetMessageType() const;
private:
   Header::MessageType m_messageType;
};

Header::Header() :
   m_messageType(Header::MessageType::InvalidMessage)
{
}

Header::Header(Header::MessageType messageType) :
   m_messageType(messageType)
{
}

Header::MessageType Header::GetMessageType() const
{
   return m_messageType;
}

Select all Open in new window

Here is the derived class:

class Message : public Header
{
public:
   Message();
   ~Message() = default;

   void SetMessage(std::string message);
   std::string GetMessage() const&;

private:
   std::string m_message;
};

Message::Message() :
   Header(Header::MessageType::Message),
   m_message("")
{
}

void Message::SetMessage(std::string message)
{
   m_message = message;
}

std::string Message::GetMessage() const&
{
   return m_message;
}

Select all Open in new window

Here is how I'm acessing the function GetMessage();

int main()
{
   Reader reader;

   auto basePtr = reader.ReadAll(message);
   auto derivedPtr = std::dynamic_pointer_cast<communication::Message>(basePtr);
   std::cout << "read: " << derivedPtr->GetMessageType() << ";" << derivedPtr->GetMessage();
}

Select all Open in new window

When I try to execute GetMessage() like up above, I get the error below:

Server.cpp.obj : error LNK2019: unresolved external symbol "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall communication::Message::GetMessageA(void)const & " (?GetMessageA@Message@communication@@QGBE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ) referenced in function _main
Server.exe : fatal error LNK1120: 1 unresolved externals

Select all Open in new window

It has to do with the function GetMessage() but I'm failing to see what is wrong. If I remove that call, everything compile fine.
Also, I do the exact same call in other class and it is working fine.
Help is needed!!!

dup2(int oldfd, int newfd);

Select all Open in new window

This is an equivalent of:

close(int newfd);
dup(int oldfd);

Select all Open in new window

By closing "newfd" first, it becomes the lowest-numbered unused file descriptor (normally). Because of that the oldfd is copied to newfd (dup system call). So far, everything is clear.

Now see: http://codewiki.wikidot.com/c:system-calls:dup2

dup2 is a system call similar to dup in that it duplicates one file descriptor, making them aliases, and then deleting the old file descriptor.

Actually I don't think the old file descriptor will be deleted?

See: http://man7.org/linux/man-pages/man2/dup.2.html

After a successful return, the old and new file descriptors may be used interchangeably.

If the old file descriptor will be deleted, then they would not say something like that. Is wikidot.com just wrong about this?

Dear experts,

I am learning C++

I have some idea about Objects in C++

Is there an online course which can teach me 'objects' and ' Data Structures' in great detail?

Kindly suggest.

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();
         ^