View Compilation Error

0_0_20960745_13315.cpp: In function 'void makeprime()':
0_0_20960745_13315.cpp:15:46: error: 'memset' was not declared in this scope
  memset(isnotprime, false, sizeof(isnotprime));
                                              ^
0_0_20960745_13315.cpp: In function 'int main()':
0_0_20960745_13315.cpp:33:28: error: 'memset' was not declared in this scope
  memset(gcd, 0, sizeof(gcd));
                            ^