Undefined reference to pow in C despite including math h

Question

Possible Duplicate    Problem using pow   in C   what is   39 undefined reference to  pow  39   39        I m having a bit of an issue with a simple piece of coursework for uni that s really puzzling me   Essentially  I ve to write a program that  amongst other things  calculates the volume of a sphere from a given radius  I thought I d use the pow   function rather than simply using r r r  for extra Brownie points  but the compiler keeps giving me the following error      undefined reference to  pow    collect2  error  ld returned 1 exit status   My code looks like the following    include  lt math h gt    define PI 3 14159265   defines the value of PI     Declare the functions    double volumeFromRadius double radius       Calculate the volume of a sphere from a given radius    double volumeFromRadius double radius        return  4 0 3 0    PI   pow radius 3 0f       and I m compiling with the command gcc -o sphere sphere c  This compiles and runs fine in code  blocks on the Windows machines at uni  but on my Fedora 17 at home the command line compiler refuses to run  Any thoughts would be gratefully appreciated   Blessings  Ian

User · Accepted Answer

You need to link with the math library   gcc -o sphere sphere c -lm   The error you are seeing  error  ld returned 1 exit status is from the linker ld  part of gcc that combines the object files  because it is unable to find where the function pow is defined   Including math h brings in the declaration of the various functions and not their definition  The def is present in the math library libm a  You need to link your program with this library so that the calls to functions like pow   are resolved

[c] Undefined reference to pow( ) in C, despite including math.h

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