/in/foo.cc: In constructor 'BinTree::BinTree(char*, char*)':
/in/foo.cc:21:21: error: 'strlen' was not declared in this scope
   int n = strlen(pre);
                     ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:109:28: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
  BinTree T("ABDEC", "DEBAC");
                            ^
/in/foo.cc:109:28: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
/in/foo.cc:114:10: error: expected '}' at end of input
  return 0;
          ^