View Compilation Error

0_0_16208052_16607.cpp: In function 'int main()':
0_0_16208052_16607.cpp:9:23: error: 'memset' was not declared in this scope
   memset(n,0,sizeof(n));
                       ^
0_0_16208052_16607.cpp:10:21: error: 'strlen' was not declared in this scope
   int len=strlen(buf);
                     ^