View Compilation Error

0_0_20767656_31872.cpp: In constructor 'node::node()':
0_0_20767656_31872.cpp:13:38: error: 'memset' was not declared in this scope
 #define mst(a,b) memset(a,b,sizeof(a))
                                      ^
0_0_20767656_31872.cpp:40:16: note: in expansion of macro 'mst'
  node(){now="";mst(ta,0);mst(tb,0);val=0;};
                ^
0_0_20767656_31872.cpp: In constructor 'node::node(std::string)':
0_0_20767656_31872.cpp:13:38: error: 'memset' was not declared in this scope
 #define mst(a,b) memset(a,b,sizeof(a))
                                      ^
0_0_20767656_31872.cpp:41:24: note: in expansion of macro 'mst'
  node(string s):now(s){mst(ta,0);mst(tb,0);val=cal(now);}//pt(now);pt(val);pt(occ[now]);}
                        ^