From: jameskuyper@alumni.caltech.edu   
      
   On 2025-12-22 07:18, Janis Papanagnou wrote:   
   > On 2025-12-22 12:44, James Kuyper wrote:   
   >> On 2025-12-22 03:48, Michael Sanders wrote:   
   >>> Is it incorrect to use 0 (zero) to seed srand()?   
   >>>   
   >>> int seed = (argc >= 2 && strlen(argv[1]) == 9)   
   >>> ? atoi(argv[1])   
   >>> : (int)(time(NULL) % 900000000 + 100000000);   
   >>>   
   >>> srand(seed);   
   >>   
   >> No, why whould you think so?   
   >   
   > There's number sequence generators that produce 0 sequences if seeded   
   > with 0. ...   
      
   The details of how the seed affects the random number sequence are   
   unspecified by the standard. I personally would consider a pseudo-random   
   number generator to be quite defective if there were any seed that   
   produced a constant output.   
      
   > ... And maybe the comment in 'man 3 rand', "If no seed value is   
   > provided, the rand() function is automatically seeded with a value   
   > of 1.", may have fostered his doubt.   
      
   The C standard explains that as follows: "If rand is called before any   
   calls to srand have been made, the same sequence shall be generated as   
   when srand is first called with a seed value of 1." (7.24.2.2p2).   
      
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