View Compilation Error

0_0_4822213_19851.cpp: In constructor `node<DataType>::node()':
0_0_4822213_19851.cpp:12: error: `NULL' undeclared (first use this function)
0_0_4822213_19851.cpp:12: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_4822213_19851.cpp: In constructor `node<DataType>::node(DataType)':
0_0_4822213_19851.cpp:13: error: `NULL' undeclared (first use this function)
0_0_4822213_19851.cpp: In function `void OutOfRange()':
0_0_4822213_19851.cpp:39: error: `cout' undeclared (first use this function)
0_0_4822213_19851.cpp:39: error: `endl' undeclared (first use this function)
0_0_4822213_19851.cpp: In member function `void DLinkList<DataType>::traverse()':
0_0_4822213_19851.cpp:139: error: `cout' undeclared (first use this function)
0_0_4822213_19851.cpp:146: error: `endl' undeclared (first use this function)