View Compilation Error

0_0_16447655_4105.cpp: In function 'int main()':
0_0_16447655_4105.cpp:15:40: error: 'memset' was not declared in this scope
 #define MemX(x) memset(x,0x3f,sizeof(x))
                                        ^
0_0_16447655_4105.cpp:25:7: note: in expansion of macro 'MemX'
       MemX(dis);
       ^