problem with gcc/glibc (?)

[pafLaXe]

hello all

i run a fedora core 3 newly installed
I'm new to gcc, i used to compile my program under borland c/c++ until yet.
i have a problem compiling my programs with gcc.

look at this example :

#include <math.h>

int main(void) {
float toto = 3.23;
float titi;

titi = floorf(toto);
}

when i try to compile it with :

$ gcc -o test test.c

i get :

/tmp/ccGtZYgC.o(.text+0x2b): In function `main':
: undefined reference to `floorf'
collect2: ld returned 1 exit status

and this is just an example, i tried with several other headers and i get this type of error with whatever function i use...

can someone help me ?
thx !!

vince

[tashirosgt]

Try
gcc -o test tes.c -lm
You need a command like -lxyz to link a library named libxyz. The math functions are in libm, so you need the -lm option.
Getting programs to compile and link requires almost as much study as learning programming. After you have done some simple ones from the command line, you'll want to learn the fundamentals of the gnu make utility (not a simple thing either).

[pafLaXe]

thanks ! Sure i will (try) to learn gnu make... one day...

[PompeyBlue]

If you want

float x = 3.23;

then you should type

float x = 3.23f;

Otherwise the compiler casts your float to a "double float" which is generally slower on most architectures to compute. Adding the 'f' suffix ensures it's a true float (32 bits) and therefore runs much faster.