View Compilation Error

0_0_18236741_15928.cpp: In function 'void insert(char*, Node*&)':
0_0_18236741_15928.cpp:23:23: error: 'strlen' was not declared in this scope
  int len = strlen(tire);
                       ^
0_0_18236741_15928.cpp: In function 'bool search(char*, Node*&)':
0_0_18236741_15928.cpp:48:23: error: 'strlen' was not declared in this scope
  int len = strlen(tire);
                       ^