View Compilation Error

0_0_37262816_17226.cpp: In function 'int main()':
0_0_37262816_17226.cpp:12:27: error: 'memset' was not declared in this scope
 memset(buf, 0, sizeof(buf));
                           ^
0_0_37262816_17226.cpp:15:21: error: 'strlen' was not declared in this scope
 int len = strlen(buf);
                     ^