Unable to change the settimer value - c++

Question

I am using settimer to start the timer. I want to change the timer value everytime the timer lapses.
The code is as below:
#include<iostream>
#include <windows.h>
#include <stdio.h>
#include<WinUser.h>
#pragma comment( lib, "user32.lib" )
void main()
{
int id = 1;
static bool isStart = false;
static long l = 10000;
while(1)
{
int n;
MSG msg = {0};
{
SetTimer(NULL, id,l,NULL);
while(GetMessage(&msg,NULL, 0,0))
{
// Post WM_TIMER messages to the hwndTimer procedure.
if (msg.message == WM_TIMER)
{
std::cout << "Timer expired";
KillTimer(NULL, id);
msg.message = 0x0;
l = 20000;
break;
}
}
}
}
}
Even though I change the value to 20000 its not taking, the timer is set only once.
Need help on this.
Thanks

Answer 1

You need to use the return value of SetTimer to kill the timer
int main(int argc, char **argv)
{
static bool isStart = false;
static long l = 5000;
while(1)
{
int n;
MSG msg = {0};
UINT_PTR p = SetTimer(NULL, 0,l,NULL);
while(GetMessage(&msg,NULL, 0,0))
{
// Post WM_TIMER messages to the hwndTimer procedure.
if (msg.message == WM_TIMER)
{
std::cout << "Timer expired" << std::endl;
KillTimer(NULL, p);
msg.message = 0x0;
l = 20000;
break;
}
}
}
}
SetTimer From MSDN
Return value
Type: Type: UINT_PTR If the function succeeds and the hWnd parameter
is NULL, the return value is an integer identifying the new timer. An
application can pass this value to the KillTimer function to destroy
the timer.