Compilare: main.cpp: In function 'int main()': main.cpp:17:21: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(s+1,N,fin); ^ In file included from /usr/include/stdio.h:936:0, from /usr/include/c++/6/cstdio:42, from /usr/include/c++/6/ext/string_conversions.h:43, from /usr/include/c++/6/bits/basic_string.h:5420, from /usr/include/c++/6/string:52, from /usr/include/c++/6/bits/locale_classes.h:40, from /usr/include/c++/6/bits/ios_base.h:41, from /usr/include/c++/6/ios:42, from /usr/include/c++/6/ostream:38, from /usr/include/c++/6/iostream:39, from main.cpp:1: In function 'char* fgets(char*, int, FILE*)', inlined from 'int main()' at main.cpp:17:21: /usr/include/x86_64-linux-gnu/bits/stdio2.h:261:58: warning: call to '__fgets_chk_warn' declared with attribute warning: fgets called with bigger size than length of destination buffer return __fgets_chk_warn (__s, __bos (__s), __n, __stream); ^