View Compilation Error

0_0_11547475_216.cpp: In constructor `node::node()':
0_0_11547475_216.cpp:8: error: `nullptr' undeclared (first use this function)
0_0_11547475_216.cpp:8: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_11547475_216.cpp: In destructor `node::~node()':
0_0_11547475_216.cpp:16: error: `nullptr' undeclared (first use this function)
0_0_11547475_216.cpp: In member function `void actrie::insert(const char*)':
0_0_11547475_216.cpp:36: error: `nullptr' undeclared (first use this function)
0_0_11547475_216.cpp: In member function `void actrie::make()':
0_0_11547475_216.cpp:46: error: `nullptr' undeclared (first use this function)
0_0_11547475_216.cpp: In member function `int actrie::query(const char*) const':
0_0_11547475_216.cpp:72: error: `nullptr' undeclared (first use this function)