how to get log2 of a value

Hi,
Can anyone tell me how to get log of a value in C.
log function works only in .cpp files not in .c file

thanks

What?!?! Do you mean the logarithm?

yes..logarithm

Use log() or log10() funcitons declared in math.h. Doesn't that work?

thanks ..it works.i was making a mistake:o