View Compilation Error

0_0_13469226_31896.cpp: In function 'int main()':
0_0_13469226_31896.cpp:18:38: error: 'strcmp' was not declared in this scope
     while(gets(str)&&strcmp(str,"END")!=0)
                                      ^
0_0_13469226_31896.cpp:22:23: error: 'strlen' was not declared in this scope
         len=strlen(str);
                       ^