Can someone explain the following piece of code
int x = 45;
int y = x &= 34;
It assigns 32 to y
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Probably accidental rollback by OPmafu– mafu2010-05-17 09:04:18 +00:00Commented May 17, 2010 at 9:04
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7 Answers
It's performing a bitwise "and" as a compound assignment operator. It's equivalent to:
int x = 45;
x = x & 34;
int y = x;
Now 45 = 32 + 8 + 4 + 1, and 34 = 32 + 2, so the result of a bitwise "and" is 32.
Personally I think that using a compound assignment operator in a variable declaration is pretty unreadable - but presumably this wasn't "real" code to start with...
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slugster
Dammit, you can't compete with the Skeet! (needs to be added here: meta.stackexchange.com/questions/9134/jon-skeet-facts). When 10 people including @Jon answer a question simultaneously, only he will walk away with 2+ Nice Answer badges.... and all before morning tea time (in London time). Nice :)
int x = 45;
int y = x &= 34;
Gives: y = 32
int x = 45; // 45 = 101101
// 34 = 100010
x = x & 34; // 101101
// 100010 &
// --------
// 100000 ( = 32 )
int y = x; // y = 32
Comments
It's a bitwise operation, more information can be found here:
http://msdn.microsoft.com/en-us/library/sbf85k1c%28VS.80%29.aspx
Comments
It is equivalent to:
int x = 45;
x = x & 34;
int y = x;
The & operator for integral types computes the logical bitwise AND of its operands.
Comments
Looks like a bitwise AND, which is assigned to x by the &= shortcut notation, and is also assigned to y.
Comments
Here x &= 34 is used both as an assignment and an expression. It calculates the value of x & 34, assigns it to x, and the value of the expression is what's assigned.
The result of the bitwise and operation 45 & 34 is 32, which is assigned to x, and then also to y.
Comments
45 = 101101(binary)
34 = 100010(binary)
45 & 34 = 100000(binary) = 32
