View Compilation Error

0_0_19835498_23757.cpp: In function 'int main()':
0_0_19835498_23757.cpp:6:36: error: 'memset' was not declared in this scope
 #define m(a,b) memset(a,b,sizeof(a))
                                    ^
0_0_19835498_23757.cpp:15:9: note: in expansion of macro 'm'
         m(p,-1);
         ^