View Compilation Error

0_0_21558568_22005.cpp: In function 'int maxmatch()':
0_0_21558568_22005.cpp:30:31: error: 'memset' was not declared in this scope
     memset(cx, 0xff, sizeof cx);//初始值为-1表示两个集合中都没有匹配的元素！
                               ^
0_0_21558568_22005.cpp: In function 'int main()':
0_0_21558568_22005.cpp:48:33: error: 'memset' was not declared in this scope
         memset(mp, 0, sizeof(mp));
                                 ^