View Compilation Error

0_0_30341876_12100.cpp: In function 'int main()':
0_0_30341876_12100.cpp:15:15: error: 'strlen' was not declared in this scope
   n = strlen(s);
               ^
0_0_30341876_12100.cpp:16:29: error: 'memset' was not declared in this scope
   memset(res, 0, sizeof(res));
                             ^