Compilare: user.cpp: In function ‘int main()’: user.cpp:9:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%d",&n); ^ user.cpp:11:28: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%c",&ch[0]); ^ user.cpp:12:27: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(ch+1,500001,fin); ^ In file included from /usr/include/stdio.h:934:0, from user.cpp:1: In function ‘char* fgets(char*, int, FILE*)’, inlined from ‘int main()’ at user.cpp:12:27: /usr/include/i386-linux-gnu/bits/stdio2.h:253:58: warning: call to ‘__fgets_chk_warn’ declared with attribute warning: fgets called with bigger size than length of destination buffer [enabled by default] return __fgets_chk_warn (__s, __bos (__s), __n, __stream); ^