Re: sqrt C function(clarification)

[Shaul Karl <shaulka@bezeqint.net>]

> I'm sorry not to have provided more information in my first e-mail although 
> i'm very glad so many people responded to help, but i've done some more 
> testing:
> 
> specifically i'm getting 'prase error in tmp/x' where x is a long string of 
> characters that tends to change on every run of the complier (at least when 
> i'm compiling other programs). I've tried the following and gotten no errors
> 
> #include <stdio.h>
> #include <math.h>
> 
> double num=16.0;
> 
> int main()
> { 
>      double sqrt(double num);
> return(0);
> }
> 
> the following warns me that 'function sqrt does not match global variable' 
> but still compiles
> 
> #include <stdio.h>
> #include <math.h>
> 
> float num;
> 
> int main()
> { 
>      float sqrt(float num);
> return(0);
> }
> 
> and this one just doesn't work at all giving the parse error previously 
> described:
> 
> #include <stdio.h>
> #include <math.h>
> 
> double num;
> 
> int main()
> { 
>       num = 16; /*i've also tried 16. and 16.0 here*/
>       double sqrt(double num);
> return(0);
> }
> 


[12:13:02 tmp]$ cat sqrt.c
#include <stdio.h>
#include <math.h>

double num;

int main()
{ 
      num = 16; /*i've also tried 16. and 16.0 here*/
      double sqrt(double num);
return(0);
}
[12:13:10 tmp]$ gcc -Wall sqrt.c -o sqrt -lm
sqrt.c: In function `main':
sqrt.c:9: parse error before `double'
[12:13:25 tmp]$ gcc -v
Reading specs from /usr/lib/gcc-lib/i386-linux/2.95.4/specs
gcc version 2.95.4 20010319 (Debian prerelease)
[12:21:32 tmp]$ 

You can not have a deceleration (double sqrt(double);) after a command (num = 
16;) in the same block. Replacing the order of
    num = 16
and 
    double sqrt(double num);
fixed the warning for me. I can not reproduce the tmp/x error you are 
reporting. Maybe you should try to type the whole file from scratch, possibly 
in another dir?


> I'm sorry I was not more clear with my first e-mail and hope this points out 
> the problem better.  Also, how do I let gcc know that I want math.h to be an 
> available library so i dont' have to use the -l option every time if run it?
> 


Do not know the answer for getting -lm by default. You might try info gcc. 
This will not be an issue with larger projects since one would use make:

[12:29:37 tmp]$ cat Makefile 
CFLAGS  = -Wall
LDFLAGS = -lm

sqrt:    sqrt.c
        cc -o $@ $< $(CFLAGS) $(LDFLAGS)
[12:29:39 tmp]$ make
cc -o sqrt sqrt.c -Wall -lm
[12:29:46 tmp]$


> one final thing: did any of you try comiling the non-working examples on your 
> gcc's? did you get any errors?
> 
> thanks a lot
> 
> 
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-- 

	Shaul Karl <shaulka@bezeqint.net>