View Compilation Error

0_0_29656607_31148.cpp: In function 'int main()':
0_0_29656607_31148.cpp:2:41: error: 'memset' was not declared in this scope
 #define mes(x, m) memset(x, m, sizeof(x))
                                         ^
0_0_29656607_31148.cpp:52:9: note: in expansion of macro 'mes'
         mes(mat,0);
         ^