Re: [Dev-C++] Another pointer question (I think its an compiler issue)

[<or...@vp...>]

Christian Schmidt wrote:
> Look at and perhaps run the commented source code:

There are a few errors about your code. You should enable -Wall, and 
correct ALL WARNINGS ALWAYS! Warnings are most often needs to be treated 
as errors! They show poor desing. I will mark the errors inside the 
quoted code:

> #include <stdio.h>
>  
> main ( )
> {
>   double flt_num, *flt_ptr; 
>   
>   flt_num = 123,45;
/* Use a period "." for floating-point values instead of comma "," */
>  
>   /* This bit shows (prints) the value of flt_num and then
>   it's adress in memory */
>  
>   printf ("flt_num = %f.\n",flt_num);
>   printf ("The adress of flt_num is %p.\n",&flt_num);
>  
>   /* Assigning the pointer to the variable flt_num  */
>  
>   flt_ptr = &flt_num;
>  
>  
>   /* Setting to value of flt_num via a pointer variable to the
>   new value */
>  
>   *flt_ptr = 543,21;
/* Use a period "." for floating-point values instead of comma "," */
>  
>   /* Here comes my problem. If I would ask for the value of the pointer.
>   Its called flt_ptr btw. In theory it should show the memory address of
>   the variable flt_num. But in MSV++ 6 it shows 0.000000 and in DevCPP the
>   value of *flt_ptr. Is this a feature or a bug? */
>  
>   /* Now I'm priting the value of the pointer to screen */
> 
>   printf ("flt_ptr = %f.\n",flt_ptr); /* This should be == to &flt_num but it isn't! */
/* This line has an error. Try this:
    printf ("flt_ptr = %p.\n",flt_ptr);
    You should print it out as a pointer, NOT as a double. The compiler
    will warn you about this.
*/
>  
>   printf ("The adress of flt_ptr is %p.\n",&flt_ptr);
>  
>   printf ("*flt_ptr = %f.\n", *flt_ptr);
>  
>   return 0;

Remember: add -Wall flag for the compiler ALWAYS!

--
Greetings,
E.