Programming

Hey all,

How do I link the math library in a gnu make makefile? I have tried using -lm with the CFLAGS varibale - flags like -Wall and -ggdb work, but -lm does not. I am running gcc - 4.1.2 on a linux machine.

Ok, sorry for the wasted space, in the previous post; I should have supplied more info in the OP.

Anyway, I was fiddling around with strtod, and I wanted to test against the macro HUGE_VALF, which I determined would require math.h being included. When I got a warning that HUGE_VALF was undeclared, I assumed that it was to do with linking the math headers (the old -lm thing) from make being a problem. As it turns out, it would appear that this macro is GNU specific, (?) and as such I needed to #define _ISOC99_SOURCE as well as use the -std=c99 flag while compiling...

What exactly goes wrong?
Are you using gmake's implicit build rules?
Libraries need to be linked at the link phase of the build rather than the compile phase. CFLAGS is used for compiler flags. Use LDFLAGS to set flags for the linker:

Code:

LDFLAGS=-lm

Otherwise you can write your own make rules: Here is one example
https://www.unix.com/unix-dummies-que...-makefile.html.