Compilare: user.c: In function ‘main’: user.c:19:3: warning: passing argument 1 of ‘printf’ from incompatible pointer type [enabled by default] printf(out,"%d",x); ^ In file included from /usr/include/stdio.h:934:0, from user.c:1: /usr/include/i386-linux-gnu/bits/stdio2.h:103:1: note: expected ‘const char * restrict’ but argument is of type ‘struct FILE *’ printf (__const char *__restrict __fmt, ...) ^ user.c:21:3: warning: passing argument 1 of ‘printf’ from incompatible pointer type [enabled by default] printf(out,"%d",-1); ^ In file included from /usr/include/stdio.h:934:0, from user.c:1: /usr/include/i386-linux-gnu/bits/stdio2.h:103:1: note: expected ‘const char * restrict’ but argument is of type ‘struct FILE *’ printf (__const char *__restrict __fmt, ...) ^ user.c:9:8: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in,"%d%d",&a,&b); ^