Compilare: user.c:31: warning: return type defaults to ‘int’ user.c: In function ‘main’: user.c:39: warning: implicit declaration of function ‘exit’ user.c:39: warning: incompatible implicit declaration of built-in function ‘exit’ user.c:47: warning: incompatible implicit declaration of built-in function ‘exit’ user.c:41: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result user.c:70: warning: control reaches end of non-void function