DWORD start = ::GetTickCount(); // start counter

// all the things your program does

DWORD end = ::GetTickCount(); // stop counter
DWORD duration = end - start;
std::cout << "Duration: "  << duration << " ms" << std::endl;

#include <QDebug>
#include <QElapsedTimer>
#define CONCAT_(x,y) x##y
#define CONCAT(x,y) CONCAT_(x,y)

#define CHECKTIME(x)
    QElapsedTimer CONCAT(sb_, __LINE__);
    CONCAT(sb_, __LINE__).start();
    x
    qDebug() << __FUNCTION__ << ":" << __LINE__ << " Elapsed time: " <<  CONCAT(sb_, __LINE__).elapsed() << " ms.";

CHECKTIME(
    // any code
    for (int i=0; i<1000; i++)
    {
       timeConsumingFunc();
    }
)