Javascript Bitwise Operators

Question

I'm trying to figure out some differences between C# and Javascript. Ok, take this code in Javascript:

var j = 0x783a9b23;
var bt = ((16843134 ^ (16843134 - 1)) * j);

After executing this, "bt" will be 6051320169.

Now after doing this in C#:

int j = 0x783a9b23;
int bt = ((16843134 ^ (16843134 - 1)) * j);

"bt" will be 1756352873. Certainly not the same. Any ideas why Javascript is not seeing how C# sees it?

Dogbert · Accepted Answer · 2011-11-10 12:18:02Z

3

You can do this to make it work like in C#

var j = 0x783a9b23;
var bt = ((16843134 ^ (16843134 - 1)) * j);
bt = bt % 2147483647

This is because in c# your integer overflows the limit of 2,147,483,647.

answered Nov 10, 2011 at 12:18

Dogbert

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2 Comments

Alex K. Over a year ago

+1 or int bt = checked((16843134 ^ (16843134 - 1)) * j); to reveal the overflow

user1039705 Over a year ago

Woah, this is sweet. Always took this type of stuff for granit for so long until now when I really need to understand lower level things as Im converting some chess code to Javascript just as an exercise to learn more. Thanks a million.

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