Compilare: user.cpp: In function ‘bool is_letter(char)’: user.cpp:6:42: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] bool is_letter(char c) { return c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z'; } ^ 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:24:29: /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); ^