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&~ in a formula.

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Anonymous user -  
[Dal] Posted messages 6122 Registration date   Status Contributor Last intervention   -
Hello,

I am constantly looking for ways to optimize my code.
This morning I came across a rather strange formula that I don't understand...

Can you explain to me what this piece of code does: 

 int nbr = (sizeof(int) -1) & ~(sizeof(int) -1) ; if (nbr ...) { [...] }


It’s mainly the "& ~" part that intrigues me, is it an operator?
What does it do?

Thank you for your insights!

Configuration: Windows / Chrome 55.0.2883.87

1 answer

  1.
    [Dal] Posted messages 6122 Registration date   Status Contributor Last intervention   1 108
     
    Hello astrocurious,

    & and ~ are two bitwise operators in C

    http://www.bien-programmer.fr/bits.htm

    Dal
    1
    1. Anonymous user
       
      Thank you very much, DAL, it's very clear on your site!
      0
    2. [Dal] Posted messages 6122 Registration date   Status Contributor Last intervention   1 108
       
      It's not my site, it's Emmanuel Delahaye's :)
      0