View Compilation Error

0_0_15654692_3317.cpp:24:2: error: expected ';' after struct definition
  }
  ^
0_0_15654692_3317.cpp: In function 'void FFT::fft(FFT::Virt*, int, int)':
0_0_15654692_3317.cpp:54:6: error: 'w' was not declared in this scope
      w = w * wn;
      ^
0_0_15654692_3317.cpp: In function 'void pre()':
0_0_15654692_3317.cpp:92:24: error: 'strlen' was not declared in this scope
  int l1 = strlen(sa + 1), l2 = strlen(sb + 1);
                        ^
0_0_15654692_3317.cpp:94:22: error: 'l2' was not declared in this scope
  for(int i = 1; i <= l2; ++i) b[i] = sb[i] - '0';b[0] = l2;
                      ^
0_0_15654692_3317.cpp:94:57: error: 'l2' was not declared in this scope
  for(int i = 1; i <= l2; ++i) b[i] = sb[i] - '0';b[0] = l2;
                                                         ^