// swap int variables a and b int a = 1; int b = 2; // save a copy of "a" you are about to clobber int swap = a; a = b; b = swap;To
// swap references a and b Thing a = new Thing( 1 ); Thing b = new Thing( 2 ); // save a copy of "a" you are about to clobber Thing swap = a; a = b; b = swap; // avoid packratting Thing( 1 ) swap = null;It is possible to swap two values without using a temporary using XOR (exclusive OR). Don’t use this technique without a serious
// Swap references a and b without a temporary // It works on the principle that if you xor // with something twice you // get back to where you started. // Note, this is slower than using a swap temp variable. int a = 17; int b = 42; a = a ^ b; b = a ^ b; // a ^ b ^ b = a a = a ^ b; // a ^ b ^ a ^ b ^ b = bIf you try to encapsulate this logic in a method, it will have no effect on the caller’s variables. You have to expand it Further, the XOR technique cannot be used on two Objects in Java, the only time there would be a pressing advantage to it. I present it more as a curiosity from a bygone age.
available on the web at:
optional Replicator mirror
Please email your feedback for publication, letters to the editor, errors, omissions, typos, formatting errors, ambiguities, unclear wording, broken/redirected link reports, suggestions to improve this page or comments to Roedy Green : . If you want your message, your name or email kept confidential, not considered for public posting, please explicitly specify that. Unless you state otherwise, I will treat your message as a letter to the editor that I may or may not publish in the feedback section. After that, it will be too late to retract it. If you disagree with something I said, especially when sending an ad-hominem attack, a rant composed mainly of obscenities or a death threat, please quote the offending passage and cite the web page where you found it, tell me why you think it is wrong, and, if possible, provide some supporting evidence. I can’t very well fix erroneous or ambiguous text if I can’t find it.
Your face IP:[126.96.36.199]
|Feedback||You are visitor number 35,132.|