View Compilation Error

0_0_17347424_4703.cpp: In function 'void getNext(const char*, int*)':
0_0_17347424_4703.cpp:11:23: error: 'strlen' was not declared in this scope
     int len = strlen(s);
                       ^
0_0_17347424_4703.cpp: In function 'int KmpSearch(const char*, const char*, int*)':
0_0_17347424_4703.cpp:24:24: error: 'strlen' was not declared in this scope
     int sLen = strlen(s);
                        ^
0_0_17347424_4703.cpp: In function 'int main(int, char**)':
0_0_17347424_4703.cpp:52:27: error: 'strlen' was not declared in this scope
         int len = strlen(c);
                           ^