It wil be very rare for "CheckFrequency()" to do anything since it is called when frequency and oldFrequency are almost always equal.
if (frequency != oldFrequency) { // Did frequency cahnge?
// DO SOME STUFF
oldFrequency = frequency; // So we don't update unless needed
}
CheckFrequency();
void CheckFrequency()
{
if (frequency == oldFrequency) // Nothing's changed...
return;
}