View Compilation Error

0_0_28458301_1267.cpp: In function 'int main()':
0_0_28458301_1267.cpp:38:28: error: 'memset' was not declared in this scope
   memset(G, false, sizeof G);
                            ^
0_0_28458301_1267.cpp:43:32: error: 'strlen' was not declared in this scope
    for (int j = 2; j < strlen(s); j++)
                                ^