View Compilation Error

0_0_30333275_11323.cpp: In function 'int main()':
0_0_30333275_11323.cpp:15:19: error: 'strlen' was not declared in this scope
   ang = strlen(anf);
                   ^
0_0_30333275_11323.cpp:17:28: error: 'strstr' was not declared in this scope
   while ((p = strstr(p, anf)) != NULL) 
                            ^