Recent versions of compilers provide a great deal more warnings and errors 
than older versions for "sloppy" code, such as assigning a variable but then 
never using it. The compiler doesn't know if you made a mistake like 
misspelling a variable name or forgetting to use a variable so it prints 
warnings that previous versions of the compilers did not.

   The best way to proceed is to go through all the warnings and "fix" your 
code to prevent the warnings from appearing. It is also possible to tell the 
compiler to not warn you about some of the problems with extra compiler options 
(for example passing the compiler flag -Wno-unused-but-set-variable) but that 
is not a good solution, best to fix the code.

  Barry




> On Jul 16, 2024, at 9:54 AM, Ivan Luthfi <ivanluth...@gmail.com> wrote:
> 
> This Message Is From an External Sender
> This message came from outside your organization.
> Hello guys, 
> I am still trying to compile my old multigrid code. But i get so many 
> warning, one of those warning is like this:
> MsFEM_poisson2D_DMDA.c: In function ‘int main(int, char**)’:
> MsFEM_poisson2D_DMDA.c:185:48: warning: variable ‘finest’ set but not used 
> [-Wunused-but-set-variable]
>   185 |                         PetscInt mg_level = 2, finest;
>       |                                                ^~~~~~
> MsFEM_poisson2D_DMDA.c:56:44: warning: variable ‘pi’ set but not used 
> [-Wunused-but-set-variable]
>    56 |         PetscScalar             a,b,c,d,dt,pi;
>       |                                            ^~
> MsFEM_poisson2D_DMDA.c:57:35: warning: variable ‘Lx’ set but not used 
> [-Wunused-but-set-variable]
>    57 |         PetscInt                M,Lx,Ly,Nx,Ny,Mx,My;
>       |                                   ^~
> MsFEM_poisson2D_DMDA.c:57:38: warning: variable ‘Ly’ set but not used 
> [-Wunused-but-set-variable]
>    57 |         PetscInt                M,Lx,Ly,Nx,Ny,Mx,My;
>       |                                      ^~
> MsFEM_poisson2D_DMDA.c:58:33: warning: variable ‘hx’ set but not used 
> [-Wunused-but-set-variable]
>    58 |         PetscScalar             hx,hy,Hx,Hy;
>       |                                 ^~
> MsFEM_poisson2D_DMDA.c:58:36: warning: variable ‘hy’ set but not used 
> [-Wunused-but-set-variable]
>    58 |         PetscScalar             hx,hy,Hx,Hy;
>       |                                    ^~
> MsFEM_poisson2D_DMDA.c:58:39: warning: variable ‘Hx’ set but not used 
> [-Wunused-but-set-variable]
>    58 |         PetscScalar             hx,hy,Hx,Hy;
>       |                                       ^~
> MsFEM_poisson2D_DMDA.c:58:42: warning: variable ‘Hy’ set but not used 
> [-Wunused-but-set-variable]
>    58 |         PetscScalar             hx,hy,Hx,Hy;
>       |                                          ^~
> MsFEM_poisson2D_DMDA.c:60:58: warning: variable ‘Nondimensionalization’ set 
> but not used [-Wunused-but-set-variable]
>    60 |         PetscInt                
> Compute_finegridsolution,Nondimensionalization;
>       |                                                          
> ^~~~~~~~~~~~~~~~~~~~~
> MsFEM_poisson2D_DMDA.c:283:54: warning: ‘%d’ directive writing between 1 and 
> 11 bytes into a region of size between 0 and 99
> 
> 
> Can you guys help me to fix or solve this warning in order to get the code 
> run smoothly. Please help  
> 
> 
> -- 
> Best regards,
> 
> Ivan Luthfi Ihwani

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