View Compilation Error

0_0_22945858_15712.cpp: In function 'void mt(int)':
0_0_22945858_15712.cpp:27:25: error: 'memset' was not declared in this scope
   memset(a, 0, sizeof(a));
                         ^
0_0_22945858_15712.cpp: In function 'int main()':
0_0_22945858_15712.cpp:39:25: error: 'memset' was not declared in this scope
   memset(a, 0, sizeof(a));
                         ^