View Compilation Error

0_0_29601618_15991.cpp: In function 'int main()':
0_0_29601618_15991.cpp:24:29: error: 'memset' was not declared in this scope
         memset(a,0,sizeof(a));
                             ^
0_0_29601618_15991.cpp:28:25: error: 'strlen' was not declared in this scope
         int len=strlen(s);
                         ^