http://stackoverflow.com/a/1449355/78845

get_any_key.cpp

#include <iostream>

#if WINDOWS

#include <conio.h>

#else

#include <fcntl.h>
#include <termios.h>
#include <unistd.h>

class scoped_terminal_settings
{
public:
    scoped_terminal_settings()
        :original_terminal_state()
        ,terminal_state()
        ,original_stdin_state(0)
    {
        tcgetattr(STDIN_FILENO, &original_terminal_state);

        terminal_state = original_terminal_state;
        terminal_state.c_lflag &= ~(ICANON | ECHO);
        tcsetattr(STDIN_FILENO, TCSANOW, &terminal_state);

        original_stdin_state = fcntl(STDIN_FILENO, F_GETFL, 0);
        fcntl(STDIN_FILENO, F_SETFL, original_stdin_state | O_NONBLOCK);
    }

    ~scoped_terminal_settings()
    {
        tcsetattr(STDIN_FILENO, TCSANOW, &original_terminal_state);
        fcntl(STDIN_FILENO, F_SETFL, original_stdin_state);
    }

private:
    termios original_terminal_state, terminal_state;
    int original_stdin_state;
};


bool kbhit()
{
    scoped_terminal_settings ts;

    return EOF != getchar();
}

#endif

void get_any_key()
{
    std::cout << "Press any key to continue..." << std::endl;
    while (!kbhit())
    {
        sleep(0);
    }
}

int main()
{
    get_any_key();
}