/in/foo.cc: In function 'int main()':
/in/foo.cc:8:3: error: 'cin' was not declared in this scope
   cin>>str1;
   ^~~
/in/foo.cc:9:3: error: 'cout' was not declared in this scope
   cout<<str1.length();
   ^~~~
/in/foo.cc:11:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int i=0;i<str1.length()+1;i++){
                ~^~~~~~~~~~~~~~~~