Compilare: user.c: In function ‘main’: user.c:10:2: warning: passing argument 1 of ‘sprintf’ from incompatible pointer type [enabled by default] sprintf(fi,"%d\n%d", &a,&b); ^ In file included from /usr/include/features.h:357:0, from /usr/include/stdio.h:28, from user.c:1: /usr/include/i386-linux-gnu/bits/stdio2.h:32:1: note: expected ‘char * restrict’ but argument is of type ‘struct FILE *’ __NTH (sprintf (char *__restrict __s, __const char *__restrict __fmt, ...)) ^ user.c:10:2: warning: format ‘%d’ expects argument of type ‘int’, but argument 3 has type ‘int *’ [-Wformat=] sprintf(fi,"%d\n%d", &a,&b); ^ user.c:10:2: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘int *’ [-Wformat=]