Compilare: user.cpp: In function ‘void preKmp(std::string)’: user.cpp:17:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<x.length();++i) ^ user.cpp: In function ‘int main()’: user.cpp:59:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("strmatch.in","r",stdin); ^ user.cpp:60:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("strmatch.out","w",stdout); ^