best way to measure temperature using button

Hi guys,
I'm thinking of using a push button to measure temperature on A0 when a button connected to a digital pin on my UNO R3 is pressed.
I'm going to do it so its active LOW, and use the internal PULLUP resistor. basically I want to read the temperature sensor while the button is held, its going to work using a k type probe.

I'm not sure if its better to accumulate the temperature data and get the average value or take the last reading from just before letting go of the button.

Id need to compensate for debounce, Iwas thinking of something like this

if(button is low)
{
delay(10mS)
if(button is still low)
{
take reading
}
}

OR

f(button is low)
{
delay(10mS)
while(button is still low)
{
take reading from ADC and add to previous reading
increment counter
}
}
calculate temp and divide total by amount of readings
Reset counter.

Any thoughts or improvements on this?
Thanks

If the reading is noisy/unstable it's better to average, but you should average a known number of samples over a known period of time. (Or you could calculate a [u]moving average[/u] of a fixed number of readings.)