View Compilation Error

0_0_29290077_3240.cpp: In function 'void getFail(const char*)':
0_0_29290077_3240.cpp:15:24: error: 'strlen' was not declared in this scope
     int lenw = strlen(w);
                        ^
0_0_29290077_3240.cpp: In function 'int kmpSearch(const char*, const char*)':
0_0_29290077_3240.cpp:31:24: error: 'strlen' was not declared in this scope
     int lens = strlen(s);
                        ^