[cs631apue] non-homework: welcome.c

[Jan Schaumann]

sshah83 <sshah83 at stevens.edu> wrote:

> The second warning is about int being used as char* which implies wrong  
> type returned by getlogin() function.
>
> If I turn on all warnings using below command :
> gcc -Wall welcome.c -o welcome.out
>
> I see the exact warning leading to the implicit function declaration
> welcome.c:5:2: warning: implicit declaration of function 'getlogin'  
> [-Wimplicit-function-declaration]
>
> This warning means function prototype for getlogin() is missing and the  
> "implicit function declaration" rule in C language means that a default  
> declaration that returns int is created implicitly  
> (http://stackoverflow.com/questions/9182763/implicit-function-declarations-in-c).
>
> The fix would be to include the correct header file which has the right  
> function prototype
>
> #include <unistd.h>

Correct - well done!

Compiling with "-Wall" is always a good idea, but mandatory in this
class.  Reading and understanding the messages the compiler gives you
allows you to quickly fix these sorts of things.

-Jan