Compilare: user.cpp: In function ‘int is(std::string, int, int, int)’: user.cpp:15:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(loc + op.size() - 1 > dr) return 0; ^ user.cpp:17:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<op.size() && ok;++i) { ^ user.cpp: In function ‘int eval(int, int, int)’: user.cpp:30:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int t = lvl;t<ops.size();++t) { ^ user.cpp: In function ‘int make()’: user.cpp:63:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < s.size()) { ^ user.cpp:94:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:100:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bool.in","r",stdin); ^ user.cpp:101:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bool.out","w",stdout); ^