View Compilation Error

0_0_15073557_30104.cpp: In function 'void print()':
0_0_15073557_30104.cpp:28:9: error: 'str' was not declared in this scope
  while(!str.empty())
         ^
0_0_15073557_30104.cpp: In function 'int main()':
0_0_15073557_30104.cpp:40:7: error: 'class std::stack<char>' has no member named 'clear'
   str.clear();
       ^