View Compilation Error

0_0_19940878_26742.cpp: In member function 'void Matrix::clear()':
0_0_19940878_26742.cpp:28:35: error: 'memset' was not declared in this scope
  void clear(){memset(A,0,sizeof(A));}
                                   ^
0_0_19940878_26742.cpp: In function 'void clear()':
0_0_19940878_26742.cpp:97:22: error: 'memset' was not declared in this scope
  memset(M,0,sizeof(M));
                      ^