Picture Courtesy – Squidoo

You can use std::unique() algorithm to remove adjacent duplicate items. So at first, sort your data, then call std::unique(). Now all the duplicate data will be rearranged to end of container. Now delete the unwanted range of duplicate data. Have a look at code snippet below.

#include <vector>
#include <string>
#include <algorithm>

using namespace std;

int main(int argc, char* argv[])
{
    // Election list.
    vector<string> ElectionList;
    ElectionList.push_back( "Sam" );
    ElectionList.push_back( "John" );
    ElectionList.push_back( "Ron" );
    ElectionList.push_back( "Sam" );
    ElectionList.push_back( "John" );

    // Sort the list to make same items be together.
    sort( ElectionList.begin(), ElectionList.end());

    // Rearrange unique items to front.
    vector<string>::iterator Itr = unique(
        ElectionList.begin(),
        ElectionList.end());

    // Delete the duplicate range.
    ElectionList.erase( Itr, ElectionList.end());
}

Take care that std::unique() just removes the adjacent duplicate entries. It wont remove the entire duplicate entries present in the container. That’s why we need to sort the container at first, which will arrange all duplicate entries to adjacent locations.

Targeted Audience – Beginners.

You can use QueryPerformanceCounter(). You can get the performance counter frequency – i.e. ticks per second by calling QueryPerformanceFrequency(). Have a look at the sample CStopWatch class.

// Stop watch class.
class CStopWatch
{
public:
    // Constructor.
    CStopWatch()
    {
        // Ticks per second.
        QueryPerformanceFrequency( &liPerfFreq );
    }

    // Start counter.
    void Start()
    {
        liStart.QuadPart = 0;
        QueryPerformanceCounter( &liStart );
    }

    // Stop counter.
    void Stop()
    {
        liEnd.QuadPart = 0;
        QueryPerformanceCounter( &liEnd );
    }

    // Get duration.
    long double GetDuration()
    {
        return ( liEnd.QuadPart - liStart.QuadPart) /
                long double( liPerfFreq.QuadPart );
    }

private:
    LARGE_INTEGER liStart;
    LARGE_INTEGER liEnd;
    LARGE_INTEGER liPerfFreq;
};

int main()
{
    // Stop watch object.
    CStopWatch timer;

    // Start timer.
    timer.Start();

    // ZZzzzzz... for few seconds.
    Sleep( 3000 );
    timer.Stop();

    // Get the duration. Duration is in seconds.
    long double duration = timer.GetDuration();

    return 0;
}

Even if the sample app slept for 3 seconds, in high resolution timer, the duration is 2.9xxx seconds. Can you guess why?

Targeted Audiance – Intermediate.

Image Courtesy – reginadowntown.

Yes! You can use the api – SetConsoleTextAttribute(). See the code snippet below.

// Set text color as Yellow with white background.
SetConsoleTextAttribute(
    GetStdHandle( STD_OUTPUT_HANDLE ),
    FOREGROUND_INTENSITY              | // Set Text color
    FOREGROUND_RED | FOREGROUND_GREEN | // Text color as Yellow.
    BACKGROUND_INTENSITY              | // Set Background color
    BACKGROUND_RED | BACKGROUND_GREEN | BACKGROUND_BLUE ); // White Bg.

Please note that you can mix red/green/blue constants to make new colors. Have fun.

Targeted Audience – Beginners.

Receiving arrays by reference have special syntax. The arrayname and & symbol should be enclosed in parenthesis. And you should specify the size of array. Have a look at the following code snippet.

// Receive Array by reference.
void GetArray( int (&Array) [10] )
{
}

// Test array by reference.
void CRabbitDlgDlg::TestArray()
{
    // Pass array by reference.
    int Array[10] = { 0 };
    GetArray( Array );
}

Indeed, you can pass the array as pointer and then use it. But if you ever need to pass an array by reference, then remember this tip.

Targeted Audience – Beginners.

Yes! you can do it. First you’ve to get the current font of the text control and then enable the styles you need then set it back. Setting font is done in OnInitDialog() and new font is kept as member variable. See the code snippet below.

BOOL CStaticFontDlg::OnInitDialog()
{
	...

    // Get current font.
    CFont* pFont = GetDlgItem( IDC_STATIC_ITALIC )->GetFont();
    LOGFONT LogFont = { 0 };
    pFont->GetLogFont( &LogFont );

    // Create new font with underline style.
    LogFont.lfUnderline = TRUE;
    m_StaticFont.CreateFontIndirect( &LogFont );

	// Sets the new font back to static text.
    GetDlgItem( IDC_STATIC_ITALIC )->SetFont( &m_StaticFont );

	return TRUE;
}

Now the static text will look like this.

Don’t forget to change the Id of static text control from IDC_STATIC to something else. Or else GetDlgItem() will return invalid handle.

Targeted Audiance – Intermediate.

Picture Courtesy – elitalice.com

You can use for_each() and functors to achieve this. Check out the code snippet.

1) How to delete Vector of pointers in single line

// Necessary headers.
#include "functional"
#include "vector"
#include "algorithm"

using namespace std;

// Functor for deleting pointers in vector.
template<class T>
struct DeleteVectorFntor
{
    // Overloaded () operator.
    // This will be called by for_each() function.
    bool operator()(T x) const
    {
        // Delete pointer.
        delete x;
        return true;
    }
};

// Test Function.
void TestVectorDeletion()
{
    // Add 10 string to vector.
    vector<CString*> StringVector;
    for( int Index = 0; Index < 10; ++Index )
    {
        StringVector.push_back( new CString("Hello"));
    }

    // Now delete the vector in a single  line.
    for_each( StringVector.begin(),
              StringVector.end(),
              DeleteVectorFntor<CString*>());
}

1) How to delete Map of pointers in single line

// Necessary headers.
#include "functional"
#include "map"
#include "algorithm"

using namespace std;

// Functor for deleting pointers in map.
template<class A, class B>
struct DeleteMapFntor
{
    // Overloaded () operator.
    // This will be called by for_each() function.
    bool operator()(pair<A,B> x) const
    {
        // Assuming the second item of map is to be
        // deleted. Change as you wish.
        delete x.second;
        return true;
    }
};

// Test function.
void TestMapDeletion()
{
    // Add 10 string to map.
    map<int,CString*> StringMap;
    for( int Idx = 0; Idx < 10; ++Idx )
    {
        StringMap[Idx] = new CString("Hello");
    }

    // Now delete the map in a single  line.
    for_each( StringMap.begin(),
              StringMap.end(),
              DeleteMapFntor<int,CString*>());
}

STL is really a powerful toolkit. Isn’t it?

Targeted Audience – Intermediate.

You can use SetConsoleCursorPosition(). Check out the following sample program. It reads an integer in loop and prints the time in the right hand corner of console. Just a demonstration of Visual C++’s gotoxy().

#include "iostream"
#include "time.h"
#include "windows.h"

using namespace std;

// Set current cursor position.
void GotoXY( HANDLE StdOut, SHORT x, SHORT y )
{
    // Set the cursor position.
    COORD Cord;
    Cord.X = x;
    Cord.Y = y;
    SetConsoleCursorPosition( StdOut, Cord );
}

// Print time at the upper right corner of console.
void PrintTime()
{
    // Get handle to console output buffer.
    HANDLE hStdout = GetStdHandle( STD_OUTPUT_HANDLE );

    // Get current screen information.
    CONSOLE_SCREEN_BUFFER_INFO ScreenBufferInfo = { 0 };
    GetConsoleScreenBufferInfo( hStdout, &ScreenBufferInfo );

    // Set the cursor position to upper-right of console.
    GotoXY( hStdout, 50, 0 );

    // Get time and display it.
    time_t tim=time(NULL);
    char *s=ctime(&tim);
    cout << s;

    // Reset cursor back to position.
    GotoXY( hStdout,
            ScreenBufferInfo.dwCursorPosition.X,
            ScreenBufferInfo.dwCursorPosition.Y );
}

void main(int argc, char* argv[])
{
    // Just to provide enough space.
    cout << endl << endl;

    while( true )
    {
        // Print the time.
        PrintTime();

        // Read a value.
        int a;
        cout << "Enter number: ";
        cin >> a;
    }
}

Yes! After a short break, I’m back. You’ll soon have a happy news from me, within a week. Keep watching.

Targeted Audience – Beginners.

Yes. You can. When user starts editing tree control will send a notification message - TVN_BEGINLABELEDIT. At first you have to handle the message and in the message handler, you can get the label edit control by calling GetEditControl(). Then set the edit control style to ES_NUMBER. Then the label edit control of tree, will allow only integers as input. Have a look at the code snippet.

// Message Map.
BEGIN_MESSAGE_MAP(CRabbitDlg, CDialog)
	...
	ON_NOTIFY(TVN_BEGINLABELEDIT, IDC_TREECTRL, OnBeginlabeleditTreectrl)
END_MESSAGE_MAP()

// Begin Label edit - Message Handler.
void CRabbitDlg::OnBeginlabeleditTreectrl(NMHDR* pNMHDR,
					  LRESULT* pResult)
{
    // Get the edit control which of tree control and set
    // its style to number only.
    CEdit* pEdit = m_TreeCtrl.GetEditControl();
    if( pEdit )
    {
        // Allow only numbers
        pEdit->ModifyStyle( 0, ES_NUMBER );
    }

    *pResult = 0;
}

Feel the power!

Targeted Audience – Intermediate.

Picture Courtesy – fordesigner

Basically you have to send a WM_SYSCOMMAND to any of the windows with wParam as SC_SCREENSAVE. And what really happens in background is, the default window proc will get the message and will start the screen saver. So you can call the DefWindowProc() directly to start the screensaver. Have a look at the code snippet.

// Start the screen-saver
DefWindowProc( WM_SYSCOMMAND, SC_SCREENSAVE, 0 );

It was really a nice screensaver. May be I’ll reinstall it to see it again.

Targeted Audiance – Beginners.

Picture Courtesy – DayCad.

You have to call CView::OnCmdMsg() by passing ID_FILE_PRINT or ID_FILE_PRINT_DIRECT. If ID_FILE_PRINT is passed, the printer dialog will be shown and for ID_FILE_PRINT_DIRECT, the print will be taken directly with default printer parameters. Have a look at the code snippet.

// Get the active view.
CFrameWnd* pFrameWnd = (CFrameWnd*)AfxGetApp()->GetMainWnd();
CView* pView = pFrameWnd->GetActiveView();

if( pView != NULL )
{
    // Send Print message.
    // If you want to print directly, then change ID_FILE_PRINT
    // to ID_FILE_PRINT_DIRECT.
    pView->OnCmdMsg( ID_FILE_PRINT, 0, 0, 0 );
}

Its interesting to know MFC internals. isn’t it?

Targeted Audience – Intermediate.