View Compilation Error

0_0_36586749_13186.cpp: In function 'int main()':
0_0_36586749_13186.cpp:11:25: error: 'memset' was not declared in this scope
   memset(a, 0, sizeof(a));
                         ^
0_0_36586749_13186.cpp:14:31: error: 'strlen' was not declared in this scope
   for (int i = 0; i < strlen(a); i++) {
                               ^