Compilare: user.c: In function ‘main’: user.c:23:17: warning: passing argument 1 of ‘fprintf’ from incompatible pointer type [-Wincompatible-pointer-types] fprintf("%d",0); ^~~~ In file included from /usr/include/stdio.h:936:0, from user.c:1: /usr/include/bits/stdio2.h:95:1: note: expected ‘FILE * restrict {aka struct _IO_FILE * restrict}’ but argument is of type ‘char *’ fprintf (FILE *__restrict __stream, const char *__restrict __fmt, ...) ^~~~~~~ user.c:23:9: warning: null argument where non-null required (argument 2) [-Wnonnull] fprintf("%d",0); ^~~~~~~ user.c:24:18: warning: passing argument 1 of ‘fprintf’ from incompatible pointer type [-Wincompatible-pointer-types] else fprintf("%d",a); ^~~~ In file included from /usr/include/stdio.h:936:0, from user.c:1: /usr/include/bits/stdio2.h:95:1: note: expected ‘FILE * restrict {aka struct _IO_FILE * restrict}’ but argument is of type ‘char *’ fprintf (FILE *__restrict __stream, const char *__restrict __fmt, ...) ^~~~~~~ user.c:24:23: warning: passing argument 2 of ‘fprintf’ makes pointer from integer without a cast [-Wint-conversion] else fprintf("%d",a); ^ In file included from /usr/include/stdio.h:936:0, from user.c:1: /usr/include/bits/stdio2.h:95:1: note: expected ‘const char * restrict’ but argument is of type ‘int’ fprintf (FILE *__restrict __stream, const char *__restrict __fmt, ...) ^~~~~~~ user.c:24:5: warning: format not a string literal and no format arguments [-Wformat-security] else fprintf("%d",a); ^~~~ user.c:10:5: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fp,"%d",&a); ^~~~~~~~~~~~~~~~~~ user.c:11:5: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fp,"%d",&b); ^~~~~~~~~~~~~~~~~~