Compilare: user.cpp: In function ‘int main()’: user.cpp:86:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(inputFile.c_str(), "r", stdin); ^ user.cpp:87:45: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(outputFile.c_str(), "w", stdout); ^ user.cpp:90:33: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(S + 1, 1, NMAX, stdin); ^ In file included from /usr/include/stdio.h:934:0, from /usr/include/c++/4.8/cstdio:42, from /usr/include/c++/4.8/random:39, from /usr/include/c++/4.8/bits/stl_algo.h:65, from /usr/include/c++/4.8/algorithm:62, from user.cpp:1: In function ‘size_t fread(void*, size_t, size_t, FILE*)’, inlined from ‘int main()’ at user.cpp:90:33: /usr/include/i386-linux-gnu/bits/stdio2.h:285:71: warning: call to ‘__fread_chk_warn’ declared with attribute warning: fread called with bigger size * nmemb than length of destination buffer [enabled by default] return __fread_chk_warn (__ptr, __bos0 (__ptr), __size, __n, __stream); ^