$ g++ GameOfLife.cpp -o Prog
GameOfLife.cpp: In member function ‘void Grid::randomize_grid()’:
GameOfLife.cpp:218:28: error: ‘ULONG_MAX’ was not declared in this scope
  218 |             double prob = (ULONG_MAX - rand->rand_long()) / static_cast<double>ULONG_MAX;
      |                            ^~~~~~~~~
GameOfLife.cpp:22:1: note: ‘ULONG_MAX’ is defined in header ‘<climits>’; did you forget to ‘#include <climits>’?
   21 | #include <sstream>
  +++ |+#include <climits>
   22 |
GameOfLife.cpp:218:80: error: expected ‘(’ before ‘ULONG_MAX’
  218 |             double prob = (ULONG_MAX - rand->rand_long()) / static_cast<double>ULONG_MAX;
      |                                                                                ^~~~~~~~~
      |                                                                                (
GameOfLife.cpp:218:89: error: expected ‘)’ before ‘;’ token
  218 |             double prob = (ULONG_MAX - rand->rand_long()) / static_cast<double>ULONG_MAX;
      |                                                                                         ^
      |                                                                                         )

$ g++ --version
g++ (GCC) 11.1.0
$ uname -mor
5.15.3-arch1-1 x86_64 GNU/Linux