RE: Newbie help please

["Rakesh Kumar - Software, Noida" <rakeshku at noida dot hcltech dot com>]

It seems you hadn't linked the math library. Try -lm switch. For example

"gcc prime.c -lm"

Regards
Rakesh

> -----Original Message-----
> From: Albert van Aardt [mailto:avanaardt@free.net.nz]
> Sent: Friday, September 26, 2003 8:50 AM
> To: gcc-help@gcc.gnu.org
> Subject: Newbie help please
> 
> 
> I am trying to compile a simple C program:
> 
> #include "stdio.h"
> #include "math.h"
> 
> int number;
> 
> main()
> {
>         printf("Which number do you wish to start the test with? ");
>         scanf("%d",&number);
>         printf("\n");
>         printf("I'm starting with number %d\n",number);
>         if (number<1) number=1;
>         if (number==1) printf("1\n");
>         if (number<=2) printf("2\n");
>         if (!(number % 2)) number++;
>         if (number==1) number=3;
>         do
>         {
>                 if (isprime(number)) printf("%d\n",number);
>                 number+=2;
>         }while (1) ;
> }
> 
> isprime(int thenumber)
> {
>         int isitprime=1,loop;
>         for(loop=3 ; (isitprime) && 
> (loop<(sqrt(thenumber)+1)) ; loop+=2)
>                 isitprime = (thenumber % loop);
>         return(isitprime);
> }
> 
> 
> 
> 
> Compile it: 
> 
> gcc prime.c
> 
> but then I get this error:
> 
> 
> /tmp/ccdHcjqd.o(.text+0x128): In function `isprime':
> : undefined reference to `sqrt'
> collect2: ld returned 1 exit status
> 
> 
> I have also tried some other programs, and all seem to give 
> this "sqrt" error.  
> Clearly I am doing something stupid, but surely GCC can 
> handle square roots?
> 
> 
> Please advise!
> 
> (RedHat 9)
> 
> -- 
> 
> 
> Albert & Sue van Aardt
> Whangarei
> New Zealand
> 
> Linux rules!
>