View Compilation Error

0_0_18161822_21047.cpp: In member function 'int agent::arrange(int)':
0_0_18161822_21047.cpp:194:32: error: 'memset' was not declared in this scope
  memset(qlist, 0, sizeof(qlist));
                                ^
0_0_18161822_21047.cpp: In constructor 'agent::agent()':
0_0_18161822_21047.cpp:316:34: error: 'memset' was not declared in this scope
  memset(drooms, 0, sizeof(drooms));
                                  ^
0_0_18161822_21047.cpp: In constructor 'room::room()':
0_0_18161822_21047.cpp:340:28: error: 'memset' was not declared in this scope
  memset(req, 0, sizeof(req));
                            ^
0_0_18161822_21047.cpp: In constructor 'elevator::elevator()':
0_0_18161822_21047.cpp:348:32: error: 'memset' was not declared in this scope
  memset(btime, 0, sizeof(btime));
                                ^