GCC error : undefined reference

Question

I am trying to compile some C code on a beagleboard xm. I try to compile, but I get the error: undefined reference to 'isfinite' which is in the math.h library. This code compiles perfectly in all my other computers, and I do include -lm in my makefile.

I suspect that it may be my compiler, maybe it is an over version? On the beagleboard it's version 4.3.3, but on my computer it's 4.7.3, but I don't know how to get a later version. I thought opkg would automatically get the latest available.

Any ideas why this may be happening?

Answer 1

The function infinite() is part of C99. Your compiler is by default using an older version of the C language. You need to compile with the the flag -std=c99 to enable this macro.

`gnu89' GNU dialect of ISO C90 (including some C99 features). This is the default for C code.

http://gcc.gnu.org/onlinedocs/gcc-4.3.3/gcc/C-Dialect-Options.html

Answer 2

isfinite is part of the C++11 standard and gcc 4.3.3 is to old to know that. Try int finite(double x); or int finitef(float x);.