View Compilation Error

0_0_28826313_15862.cpp: In function 'void getsg(int)':
0_0_28826313_15862.cpp:7:38: error: 'memset' was not declared in this scope
 #define mem(a,b) memset(a,b,sizeof(a))
                                      ^
0_0_28826313_15862.cpp:19:3: note: in expansion of macro 'mem'
   mem(s, 0);
   ^
0_0_28826313_15862.cpp: In function 'int main()':
0_0_28826313_15862.cpp:7:38: error: 'memset' was not declared in this scope
 #define mem(a,b) memset(a,b,sizeof(a))
                                      ^
0_0_28826313_15862.cpp:46:3: note: in expansion of macro 'mem'
   mem(sg, 0);
   ^