c math linker problems on Ubuntu 11.10 [duplicate]

Answer 1

I found the same problem after upgrading my Ubuntu to 11.10 version. I use Netbeans for developing and solved the problem by specifying the "Mathematics" standard library as it follows:

Right click on project, click on Properties, select "Linker" on menu, click on "Libraries" and then "Add Standard Library" choosing "Mathematics".

When compiling the '-lm' option is placed after all the other options and it works. Probably this gcc version follows a specific architecture and it expects the libraries at the end of the command compiling line.

Cheers!

D.

Answer 2

SOLVED, this is not the common missing -lm problem! I'm in the same situation after upgrade to (k)ubuntu 11.10!

$ whereis math.h
math: /usr/include/math.h

Makefile:
CC=gcc
CFLAGS=--std=c99 -g -pedantic -Wall -lm

uname:
Linux idefix 3.0.0-12-generic #20-Ubuntu SMP Fri Oct 7 14:56:25 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux

You really HAVE TO place the -lm swith after -o foo foo.c parameter

Output:
pidi@idefix:~/projekt1$ make
gcc -o b1 b1.c --std=c99 -g -pedantic -Wall -lm
pidi@idefix:~/projekt1$

So swap your flags in Makefile! GUYS. This is pretty new (and serious) BUG!

Answer 3

The library that you are using needs to be placed after the files that use it when you are using it from the command line. So place -lm on after your C files on the command line.

Reference

Answer 4

This is a problem due to the default activation of the gcc flag --as-needed in the linker

More information here: http://www.gentoo.org/proj/en/qa/asneeded.xml

Simple fix (worked for me at least):

Add -Wl,--no-as-needed to the linker

Answer 5

cc filename.c -lm

just try..........☻