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| logical vs. binary operators |
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bamccaig
Member #7,536
July 2006
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The confusion comes from modern languages like ECMAScript[1] (and evidently Ruby and others). They do work as Audric described. The operation evaluates to whatever side is last evaluated (for both && and ||, IIRC). It's a little bit of a logical fallacy, I suppose, but it does result in some fun shortcuts. Search for "last value" in this Wikipedia article. References
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Audric
Member #907
January 2001
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I feel very embarrassed... By the way, I just tested with gcc on win32, and the 'booleans' produced by logical operators seem to be 4-byte size, even when not "mixed" with other data types. I tested using sizeof((1==1)) and normal optimization. |
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Arthur Kalliokoski
Second in Command
February 2005
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Heh, I remember showing an instructor in the '80's how an Apple II wouldn't accept my "MOVE A TO B" command. He points out that MOVE is a COBOL keyword (yes, studying both languages at the same time). They all watch too much MSNBC... they get ideas. |
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ImLeftFooted
Member #3,935
October 2003
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Technically || could return the second element for some given types. Also | can be used as a || for some given types. template<class C, class FalseT> C &operator ||&(C &a, C &b, FalseT f = false) { if(a) return a; if(b) return b; return f; }
Uh oh... whats going to happen now? int i = 0 || 5;
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Tobias Dammers
Member #2,604
August 2002
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Audric said: By the way, I just tested with gcc on win32, and the 'booleans' produced by logical operators seem to be 4-byte size, even when not "mixed" with other data types.
It is pretty common for compilers to base booleans on the platform's native integer type. For x86, that's a 32-bit integer. --- |
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Looks like the little of Perl that I had, years ago, has contaminated my knowledge of C 
