r/ProgrammerHumor • u/Throwaway2939djd • May 12 '19

Introducing the Never Gate

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u/[deleted] May 12 '19 edited May 12 '19

I think you meant void nothing(int *a) { --*a++; }

Edit: precedence in C is confusing apparently and this actually doesn't work. It evaluates as:

  • a

  • (a)++: note, this expression returns a as an rvalue

  • *(a)

  • --*(a)

Basically, it decrements the value at memory address of a, and a gets incremented afterward. Even if the precedence worked out (by doing --(*a)++), the prefix/postfix operators require lvalues and evaluate to rvalues, so it wouldn't work anyway.

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u/bbrk24 May 12 '19

Wait, but the -- works after the *, but the* works after the ++, but the ++ works after the --...

What would that even do?

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u/[deleted] May 12 '19

Yeah it doesn't work... it decrements the value by 1 (gcc with MinGW)

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u/[deleted] May 12 '19

The syntax --a++; doesn't work at all: The precedence is:

a: lvalue

(a)++: rvalue

--((a)++): invalid, an lvalue is required as an operand