View Compilation Error

0_0_13506863_15321.cpp: In function 'int main()':
0_0_13506863_15321.cpp:18:35: error: 'strcmp' was not declared in this scope
  while(gets(str)&&strcmp(str,"END")){
                                   ^
0_0_13506863_15321.cpp:19:23: error: 'strlen' was not declared in this scope
   int len = strlen(str);
                       ^