David Vonka wrote: > Note that the only difference is "1" instead of "K" on line 3. > I compile by following command: > > gcc blan.c -lm > > In case A the answer of gcc is > /cygdrive/c/Temp/ccEHzDhs.o:blan.c:(.text+0x30): undefined reference to > `_powl' > collect2: ld gaf exit-status 1 terug There is no need to ever use -lm under Cygwin because all math functions are in the main cygwin1.dll. Specifying -lm is a no-op. > In case B the program compiles without any problem and returns correct > answer when run. Both programs compile when substituting "pow" for > "powl". The switch "-lm" makes no difference(!), the result is exactly > the same without it. Cygwin does not provide an implementation of powl(). In case B the compiler optimized away the call to the function because it recognised that raising a number to the power of 1 does nothing. Brian
