I'd like to be able to PING from my MS C++ program.    I'd rather not do it by a command line and then parse the string response, because I think different language PCs emit a different text response, and I just need this to work on all PCs.   Ideally I want to call

int ms = Ping("192.168.1.20");

in my C++ program, and "ms" is the trip time that ping normally reports.   Or maybe I need a variant where I can set the timeout duration in ms, like:

int ms = Ping("192.168.1.20", 500);

I happen to know that this is pretty easily done in C# but I can't find how to do it from C++.

why the below code is not working in dev cpp compiler?
#include<iostream>
#include<typeinfo>
using namespace std;
class A{public:
      virtual void f(){
      }
};
class B{};
class C{
};
bool check(A* ptr){B *der;
if(der=dynamic_cast<B* >()ptr)
return true;
else return false;
}
int main(){B* d1=new B;
C* d2=new C;
if(check(d1))cout<<"ok";
else
cout<<"not ok";
return 0;      
}//error: cannot convert 'B*' to 'A*' for argument '1' to 'bool check(A*)'

If I start a task with a cancellation token, and I later set the cancellation token to "Cancel", can I then immediately dispose of the cancellation token, or do I need to wait for the task to get the "Cancel" message first?

It's appearing as if I don't need to wait for the task to get the "Cancel" message. It seems to get it anyway:

CancellationTokenSource cts = new CancellationTokenSource();
CancellationToken token = cts.Token;
mytask = Task.Run(async () => await MyEndlessTaskLoop(token), token);

...
// Then later in a button click event:
cts.Cancel();
cts.Dispose();

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Do I need to insert a wait between the "Cancel()" and "Dispose()"?

cts.Cancel();

try {
    mytask.Wait();
}
catch (AggregateException e) {
   // Expect e.InnerException to be "OperationCanceledException"
}

cts.Dispose();

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Also do I need to insert an await in front of Task.Run(...)?

mytask = await Task.Run(async () => await MyEndlessTaskLoop(token), token);

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And, is there a difference between passing the cancellation token as a parameter as opposed to just using it as a captured variable? As in:

private async Task MyEndlessTaskLoop()
{
    while(True)
    {
        ...
        this.token.ThrowIfCancellationRequested;
    }
}

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vs.:

private async Task MyEndlessTaskLoop(CancellationToken token)
{
    while(True)
    {
        ...
        token.ThrowIfCancellationRequested;
    }
}

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Is one preferred over the other?

I have been using VS 2008, and have installed VS 2015 side by side on the same computer. I have projects compiled in VS 20015 from another computer that compile just fine. But when I open those projects and try to compile them in the new VS 2015 on this computer they will not compile. In fact, even creating the simplest "Hello world" application will not compile.

I get errors on standard VS header files. For example, it throws errors and warnings on Windows.h like:

Warning      C4067      unexpected tokens following preprocessor directive - expected a newline      windows.h            

Error      C2061      syntax error: identifier 'LPCSTR'      
Error      C2061      syntax error: identifier 'BYTE'      

I can't figure out why this is happening. Anyone have an idea?

I am a newbie in the data structure, I have read the implementation of stack using a simple array, the algorithm for this implementation is below:-

 Stack Operations using Array

A stack can be implemented using array as follows...

Before implementing actual operations, first follow the below steps to create an empty stack.

Step 1: Include all the header files which are used in the program and define a constant 'SIZE' with specific value.

Step 2: Declare all the functions used in stack implementation.

Step 3: Create a one dimensional array with fixed size (int stack[SIZE])

Step 4: Define a integer variable 'top' and initialize with '-1'. (int top = -1)

Step 5: In main method display menu with list of operations and make suitable function calls to perform operation selected by the user on the stack.

push(value) - Inserting value into the stack

In a stack, push() is a function used to insert an element into the stack. In a stack, the new element is always inserted at top position. Push function takes one integer value as parameter and inserts that value into the stack. We can use the following steps to push an element on to the stack...

Step 1: Check whether stack is FULL. (top == SIZE-1)

Step 2: If it is FULL, then display "Stack is FULL!!! Insertion is not possible!!!" and terminate the function.

Step 3: If it is NOT FULL, then increment top value by one (top++) and set stack[top] to value (stack[top] = value).

pop() -…

When building code, I am not seeing my changes.  I've changed a simple Text Header on a page and ran the code and it does not change.
I've cleared my cache, restarted, tried a clean build and am at a loss as to what cold be causing this.

We have tested and this is only happening on React JSX pages.  It doesn't look like Webpack is compiling the changes but rather old code.

As per c++ primer book the description of writing stream opearator(<<) is-

std::cout << "Enter two numbers:" << std::endl;

 The << operator takes two operands: The left-hand operand must be an ostream object; the right-hand operand is a value to print. The operator writes the given value on the given ostream. The result of the output operator is its left-hand operand. That is, the result is the ostream on which we wrote the given value. Our output statement uses the << operator twice. Because the operator returns its left-hand operand, the result of the first operator becomes the left-hand operand of the second. As a result, we can chain together output requests.

I can't understand the above description. That is why we need two operators because one << operator is enough to print the values?

Hi Experts,

i am currently trying to compile an existing C++ project with Framemaker Development kit 2017. The earlier project was compiled with Framemaker dev kit 2015. However, whenever I am trying to compile the project I receive the following error. I think its a linking error but I tried almost all possible combinations to compile.

I am using Visual Studio 2013 ultimate since the FDK2017 lib need minimum VS2013 to compile.

Error	86	error LNK1120: 59 unresolved externals	C:\test\Project\Release 2015\Launcher.exe	Launcher
Error	28	error LNK2001: unresolved external symbol "__declspec(dllimport) __int64 const std::_BADOFF" (__imp_?_BADOFF@std@@3_JB)	C:\test\Project\Launcher\Launcher.obj	Launcher
Error	36	error LNK2001: unresolved external symbol "__declspec(dllimport) bool __cdecl std::uncaught_exception(void)" (__imp_?uncaught_exception@std@@YA_NXZ)	C:\test\Project\Launcher\Launcher.obj	Launcher
Error	22	error LNK2001: unresolved external symbol "__declspec(dllimport) char const * __cdecl std::_Syserror_map(int)" (__imp_?_Syserror_map@std@@YAPBDH@Z)	C:\test\Project\Launcher\struct.lib(strUtils.obj)	Launcher
Error	23	error LNK2001: unresolved external symbol "__declspec(dllimport) char const * __cdecl std::_Syserror_map(int)" (__imp_?_Syserror_map@std@@YAPBDH@Z)	C:\test\Project\Launcher\fdk.lib(pathmap.obj)	Launcher
Error	24	error LNK2001: unresolved external symbol "__declspec(dllimport) char const * __cdecl std::_Syserror_map(int)" 

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…

I have a dll written in Delphi that I need to call from a c++ program. My dll works when called from Delphi, both when using static and dynamic loading. However, in c++, LoadLibrary returns a null pointer. In both cases, test.dll is located in the same dir as the test program. I am a c++ beginner - any help is appreciated.

The dll:

library test;

uses
  System.SysUtils,
  System.Classes;

{$R *.res}
 function AddIntegers(_a, _b: integer): integer; stdcall;
begin
  Result := _a + _b;
end;

exports
  AddIntegers;

begin
end.

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The Delphi test program - this return the line "3 + 4 is 7", as expected:

program SimpleDLLTest;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils, Winapi.Windows;

type
  TAddIntegersFunc = function (_a, _b: integer): integer; stdcall;
var
  DllHandle : HMODULE;
  AddIntegersFunc : TAddIntegersFunc;
  TestInt         : integer;
begin
  try
    DllHandle := LoadLibrary(pWideChar('test.dll'));
    if DllHandle = 0 then begin
      Writeln('Error loading dll');
    end else begin
      @AddIntegersFunc := GetProcAddress(DllHandle, 'AddIntegers');
      if assigned(AddIntegersFunc) then begin
        TestInt := AddIntegersFunc(3,4);
        Writeln('3 + 4 is ' + IntToStr(TestInt));
      end else begin
        Writeln('Function not found');
      end;
    end;
    Write('Press Enter'); ReadLn;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
end.

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The c++ test program:

#include <windows.h>
#include <iostream>
using namespace std;

int main()
{
	HINSTANCE hGetProcIDDLL = LoadLibrary("test.dll");

	if (!hGetProcIDDLL)
	{
		cout<<"Could not load library!\n";
		cin.get();
	}
	else
	{
		cout<<"Library loaded!\n";
		cin.get();
	}

	return 0;
}

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I did not write any function call in c++, since I have not yet even managed to load the library - I just get "Could not load library".

How do you Switch Views within the same Child Frame?  C++ VS2018 15.5.6  I am using the MFC Doc/View Architecture.  I can create new 7 document, as programed.  I have seen several different code examples for do it within the Main Frame, however not within the Child Frame class.  I have created several different CView based classes.  I have added the #include(s) for them in the App.h file header, and this header is included in the ChildFm.cpp file.  It shows up OK as far as Intellisense is concerned.  
// ChildFrm.cpp : implementation of the CChildFrame class
//
#include "stdafx.h"
#include "TCPG.h"
#ifdef _DEBUG
#define new DEBUG_NEW
#endif

// CChildFrame
IMPLEMENT_DYNCREATE(CChildFrame, CMDIChildWndEx)
BEGIN_MESSAGE_MAP(CChildFrame, CMDIChildWndEx)
      ON_COMMAND(ID_VIEW_PLAYERVIEW, &CChildFrame::OnViewPlayerview)
      ON_COMMAND(ID_VIEW_QUESTIONVIEW, &CChildFrame::OnViewQuestionview)
      ON_COMMAND(ID_VIEW_LAYOUTVIEW, &CChildFrame::OnViewLayoutview)
      ON_COMMAND(ID_VIEW_YOURREADING, &CChildFrame::OnViewYourreading)
END_MESSAGE_MAP()
These are the function declarations for switching the views.  The empty bodies are in the .cpp file.
And all of it compiles OK at this point.  Each view class is filled with all of the necessaries for that class, and works with the CDocument class.
Yet ...  when I add
// ChildFrm.h : interface of the CChildFrame class
//
#pragma once

class CChildFrame : public CMDIChildWndEx
{
      DECLARE_DYNCREATE(CChildFrame)
public:
      …

Hi
I'm trying to Create a Simple Frame window using CFrameWnd Class.  in the OnCreate() function I'm Writing  code to Create Button using CButton:: Create() function but in that function
it taking parent window handle ...how do I find the handle of the Frame window..please help me.

CButton myBtn;
      afx_msg int OnCreate(LPCREATESTRUCT lp)
      {
            //MessageBox("hello","hi",1);
            
            myBtn.Create("Click me",WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON,CRect(10,10,20,30),CFrameWnd::GetActiveView(),1);
            return 0;
      }
thank you

Hello!!!!


How to convert this;

std::string response;
char time[13];

...

response.copy(time, 13,223);
time[13] = '\0';
printf("%s\n" ,time); // this print value:1517691086218

       ????   //how to convert char time[13] to int ?

       if (time == 1517691086218){
	printf("OK %d\n" ,time);
	} else {
	printf("NOT\n %d\n" ,time);
	}

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How to convert;

char time[13] = '1517691086218'

to

int value = 1517691086218

?

Thanks...

I have an application developed by a small-ish company. The application terminates roughly every day, I analyzed the crash dump and I see heap memory corruption was detected in myapplication.exe.. Vendor is out of ideas. Server is 2012R2, any suggestions on where I could start, thanks.