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A comment on What is your favorite C programming trick? (2009). Parent comment

Re:What is your favorite C programming trick? (2009) by srgpqt on Sunday November 22, 2020 @11:13AM (#25178595)
No need to define offsetof, it’s part of <stddef.h>

Still interesting to see the trick behind it tho.

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Re:What is your favorite C programming trick? (2009) by annilt on Sunday November 22, 2020 @12:17PM (#25179096)
It’s added to the standard because macro version has undefined behavior. (yet it still works on any compiler without a problem)
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Re:What is your favorite C programming trick? (2009) by londons_explore on Sunday November 22, 2020 @03:05PM (#25180577)
I was about to ask if it was legal to dereference a null pointer and then take the address of it... I presume it is not, but I'm surprised compilers don't complain at compilation time.
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Re:What is your favorite C programming trick? (2009) by saagarjha on Monday November 23, 2020 @03:52AM (#25184819)
Dereferencing a null pointer and then immediately "undoing" it by taking its address is actually legal, I believe. I think the undefined behavior here is the member access instead of the magic sequence &* which is supposed to cancel out.
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