/in/foo.cc: In member function 'void LinkStack::Match(char*)':
/in/foo.cc:61:11: warning: unused variable 't' [-Wunused-variable]
      char t = pop();//出栈
           ^
/in/foo.cc:37:9: warning: variable 'L' set but not used [-Wunused-but-set-variable]
    char L = '\0';//左括号
         ^
/in/foo.cc:80:12: warning: unused variable 'a' [-Wunused-variable]
    if (int a = empty() == true)
            ^