clinkermath.h

Compiler says pow is undefined even when I'm linking with -lm, but compiles when

value *= pow(10, 3); // this one compiles
value *= pow(10, aVar); // this one produces this error:
                         //Number.c:(.text+0x469): undefined reference to `pow'

aVar is an int variable.

What could it be?

I'm using a makefile. I'm excecuting "make lexanc" My makefile looks like this:

lexanc:  lexandr.o lexanc.o scanner.o printtoken.o token.h lexan.h Number.o
    cc -o lexanc -lm lexandr.o lexanc.o scanner.o printtoken.o Number.o
...
Number.o: Number.c Number.h lexan.h
    cc -c Number.c

lexanc.o: lexanc.c token.h lexan.h Number.h
    cc -c lexanc.c
...

My cc version is: laygr@xxx$ cc --version cc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3

Solution

  • Libraries should come after all the objects in the compiling option. Change it to:

    lexanc:  lexandr.o lexanc.o scanner.o printtoken.o token.h lexan.h Number.o
    cc -o lexanc lexandr.o lexanc.o scanner.o printtoken.o Number.o -lm

    Note -lm has been moved to the end.