how to calculate the deference between High and LOW?

 

hello every body

i want to know how can i calculate the deference between High and LOW for last candle (High[1], Low[1]) and make it as a condition to start trade in my expert.


for example i tray the following code but didn't work


if (High[1] - Open[1] > 1)

return (1);


can any one help me??