View Compilation Error

0_0_29762805_28277.cpp: In function 'void GetNext(char*)':
0_0_29762805_28277.cpp:15:25: error: 'strlen' was not declared in this scope
     int p_len = strlen(P);
                         ^
0_0_29762805_28277.cpp: In function 'int main()':
0_0_29762805_28277.cpp:45:38: error: 'memset' was not declared in this scope
         memset(nexts,0, sizeof(nexts));
                                      ^
0_0_29762805_28277.cpp:47:27: error: 'strlen' was not declared in this scope
         int len = strlen(P);
                           ^
0_0_29762805_28277.cpp:57:30: error: 'strncpy' was not declared in this scope
             strncpy(str1,P,po);
                              ^
0_0_29762805_28277.cpp:59:33: error: 'strstr' was not declared in this scope
             if (strstr(str2,str1))
                                 ^