Compilare: user.c: In function ‘main’: user.c:43: warning: implicit declaration of function ‘exit’ user.c:43: warning: incompatible implicit declaration of built-in function ‘exit’ user.c:34: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result user.c:39: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result