Compilare: user.cpp: In function ‘int is(std::string&, int, int, int)’: user.cpp:27:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<op.size();++i) { ^ user.cpp: In function ‘int eval(int, int, int)’: user.cpp:44:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int t = lvl;t<ops.size();++t) { ^ user.cpp: In function ‘int make(std::string&, int, int)’: user.cpp:40:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:81:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("evaluare.in","r",stdin); ^ user.cpp:83:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("evaluare.out","w",stdout); ^ user.cpp:86:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",s); ^