Compilare: user.cpp: In function ‘int main()’: user.cpp:22:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<a.size();i++) ^ user.cpp:29:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<a.size();i++) ^ user.cpp:40:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=a.size();i<b.size();i++) ^ user.cpp:20:16: warning: unused variable ‘j’ [-Wunused-variable] int i,ante,j,n=0; ^ user.cpp: In function ‘int to(char)’: user.cpp:17:1: warning: control reaches end of non-void function [-Wreturn-type] } ^