Compilare: user.cpp: In function ‘int main()’: user.cpp:25:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<str.size();++i) ^ user.cpp:42:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v.size();++i) ^ user.cpp:49:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<str2.size();++i) ^