View Compilation Error

0_0_12984296_29380.cpp: In constructor `Node::Node()':
0_0_12984296_29380.cpp:10: error: `nullptr' undeclared (first use this function)
0_0_12984296_29380.cpp:10: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_12984296_29380.cpp: In destructor `Node::~Node()':
0_0_12984296_29380.cpp:19: error: `nullptr' undeclared (first use this function)
0_0_12984296_29380.cpp: In member function `void AcTrie::Insert(const char*)':
0_0_12984296_29380.cpp:47: error: `nullptr' undeclared (first use this function)
0_0_12984296_29380.cpp: In member function `void AcTrie::Make()':
0_0_12984296_29380.cpp:61: error: `nullptr' undeclared (first use this function)
0_0_12984296_29380.cpp: In member function `int AcTrie::Query(const char*)':
0_0_12984296_29380.cpp:80: error: `nullptr' undeclared (first use this function)