View Compilation Error

0_0_32505341_16557.cpp: In function 'int main()':
0_0_32505341_16557.cpp:37:25: error: 'memset' was not declared in this scope
   memset(v, 0, sizeof(v));
                         ^
0_0_32505341_16557.cpp:40:19: error: 'strlen' was not declared in this scope
   len = strlen(num);
                   ^