Non-Blocking Timer C++ - c++

Question

I'm trying to create a simple non-blocking timer in C++ that can be reset. I've google searched for a while to find some code examples but everything I find is either too complicated to understand or does not compile without extra non example code.
I have a program that logs a key press to a file, but I want this file to be written over one seconds after the key has been pressed unless another key has been pressed before the second is up.
I believe I should use Win32 timers, (I am using windows) however I can't find a simple compilable example of their use.
for example this method taken from the info page:
SetTimer(hwnd, // handle to main window
IDT_TIMER1, // timer identifier
1000, // 1-second interval
(TIMERPROC) MyTimerProc); // no timer callback
VOID CALLBACK MyTimerProc(
HWND hwnd, // handle to window for timer messages
UINT message, // WM_TIMER message
UINT idTimer, // timer identifier
DWORD dwTime) // current system time
{
// my proceedure code
FILE *OUTPUT_FILE;
OUTPUT_FILE = fopen("LOG.TXT", "w");
fprintf(OUTPUT_FILE, "%s", "");
fclose(OUTPUT_FILE);
// writes a blank text file.
KillTimer(hwnd, IDT_TIMER1); // stop timer after one call
}
doesn't compile because the IDT_TIMER1 hasnt' been defined I think.
Also, I'm not sure if this would be reset by calling it twice or would just start two separate calls 1 second apart.
Any help greatly appreciated.

Answer 1

Just use the Hardware Performance Timer, which can be quickly found via google, or if you want something more cross platform use the timegettime method, which can also be found via google, neither need a Win32 message loop.

Answer 2

You are responsible for giving ID_TIMER1 a value. I believe you (99%) also have to have a windows message loop for it to work.
Here are a couple of minimal, compilable examples.

Answer 3

The following console program works. It sets a timer using SetTimer
then loops in a message loop. The message loop receives and processes WM_TIMER messages
and the timer callback also is called for each time interval. And it does not block.
#define STRICT 1
#include <windows.h>
#include <iostream.h>
VOID CALLBACK TimerProc(HWND hWnd, UINT nMsg, UINT nIDEvent, DWORD dwTime)
{
cout << "Time: " << dwTime << '\n';
cout.flush();
}
int main(int argc, char *argv[], char *envp[])
{
int Counter=0;
MSG Msg;
UINT TimerId = SetTimer(NULL, 0, 500, &TimerProc); //SetTimer
cout << "TimerId: " << TimerId << '\n';
if (!TimerId)
return 16;
while (GetMessage(&Msg, NULL, 0, 0))
{
++Counter;
if (Msg.message == WM_TIMER)
cout << "Counter: " << Counter << "; timer message\n";
else
cout << "Counter: " << Counter << "; message: " << Msg.message << '\n';
DispatchMessage(&Msg);
}
KillTimer(NULL, TimerId);
return 0;
}

Answer 4

You don't need a window or even an event loop. Look at the WaitForSingleObject function.
Here is some code
HANDLE hStdin;
hStdin = GetStdHandle(STD_INPUT_HANDLE);
FILE *OUTPUT_FILE;
OUTPUT_FILE = fopen("LOG.TXT", "w");
bool previous_input_written = TRUE;
switch (WaitForSingleObject(hStdin, 1000) {
case WAIT_OBJECT_0:
// input happened on hStdin
if (!previous_input_written) {
// the previous input was not saved to file
fprintf(OUTPUT_FILE, ...
previous_input_written= TRUE;
}
ReadConsoleInput(hStdin, ...
previous_input_written = FALSE;
case WAIT_TIMEOUT:
// the 1000ms delay timed out, write to file
fprintf(OUTPUT_FILE, ...
previous_input_written= TRUE;
}
fclose(OUTPUT_FILE);