I'm trying to make a class that will help me calculating the delta time in my game.

dt.h:

Code:

#include <ctime>
class dt
{
public:
void SetMaxFPS(int num);
void UpdateCurrentTicks();
void UpdateLastTicks();
long GetDeltaTime();
int GetFPS();
int GetMaxFPS();
bool UpdateNeeded();
private:
long GetTicks();
int max_fps;
int current_ticks;
int last_ticks;
};

dt.cpp:

Code:

#include "dt.h"
void dt::SetMaxFPS(int i)
{
max_fps = i;
}
void dt::UpdateCurrentTicks()
{
current_ticks = GetTicks();
}
void dt::UpdateLastTicks()
{
last_ticks = current_ticks;
}
long dt::GetTicks()
{
return clock();
}
long dt::GetDeltaTime()
{
return current_ticks - last_ticks;
}
int dt::GetFPS()
{
return (current_ticks - last_ticks) * 1000;
}
int dt::GetMaxFPS()
{
return max_fps;
}
bool dt::UpdateNeeded()
{
if(current_ticks > last_ticks + max_fps/1000)
return true;
return false;
}

main.cpp:

Code:

#include "dt.h"
int main(int argc, char* argv[])
{
dt::SetMaxFPS(100);
}

And I get the next error:

Code:

error C2352: 'dt::SetMaxFPS' : illegal call of non-static member function

What am I doing wrong?