Compilare: user.cpp: In function ‘int expresie()’: user.cpp:18:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i!=a.size() && a[i]!=')'){ ^ user.cpp: In function ‘int comparare()’: user.cpp:87:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(p=0;p<a.size();p++){ ^ user.cpp:118:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int p=0;p<a.size();p++){ ^ user.cpp:140:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^