View Compilation Error

0_0_35948707_9482.cpp: In function 'void BFS()':
0_0_35948707_9482.cpp:27:28: error: 'memset' was not declared in this scope
  memset(mark,0,sizeof(mark));
                            ^
0_0_35948707_9482.cpp: In function 'int main()':
0_0_35948707_9482.cpp:76:25: error: 'memset' was not declared in this scope
   memset(a,'*',sizeof(a));
                         ^