View Compilation Error

0_0_20790204_15688.cpp: In function 'int main()':
0_0_20790204_15688.cpp:14:25: error: 'memset' was not declared in this scope
   memset(s, 0, sizeof(s));
                         ^
0_0_20790204_15688.cpp:16:21: error: 'strcmp' was not declared in this scope
   if(strcmp(str, "#") == 0)
                     ^
0_0_20790204_15688.cpp:18:23: error: 'strlen' was not declared in this scope
   int len = strlen(str);
                       ^