double exclamation mark meaning ?

Shraddha Kamat sh2008ka at gmail.com
Thu Dec 6 04:50:33 EST 2012


Hi, 

# define likely(x)  __builtin_expect(!!(x), 1)
# define unlikely(x)    __builtin_expect(!!(x), 0)

I see these !! in the above expressions. Please explain me the 
meaning of those double exclamations. What is their significance ?

-- Shraddha 





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