Highest and Lowest Price

I am having data of Stock Name , Time , Date in text/ excel format . I want to find out the Highest and lowest price of these Stocks starting from the given time of the day in exploration. How to get this done in Amibroker AFL?

Use HighestSince/LowestSince
http://www.amibroker.com/f?highestsince
http://www.amibroker.com/f?lowestsince

Example:

hs = HighestSince( DateTime() <= _DT("2017-01-02"), High );

This will give you array output (http://www.amibroker.com/guide/h_understandafl.html). If you are only interested in having the very last value you can use LastValue( hs );