CODEWITHSUNDEEP
c++
catscratch
catscratch

Reputation: 41

What is the result of a dereferenced post incremented pointer being assigned to another dereferenced post incremented pointer in c++?

I encountered code similiar to the following in a c++, and I am unsure exactly what it does.

*x++ = *y++;

x and y are references to uint32s.

I understand that ++ is the post-increment operator, and * dereferences, but am still unsure of exactly what this does.

Upvotes: 4

Views: 54

Answers (1)

David C. Rankin
David C. Rankin

Reputation: 84579

C++ Standard - 7.6.1.6 Increment and decrement expr.post.incr

Your expression *x++ = *y++; applies the postfix operator ++ to each of the pointers x and y after the assignment from *x = *y; occurs. Essentially the value of each operand is its value before any increment is applied. The increment is applied after the value computation.

The standard language is:

1 The value of a postfix ++ expression is the value of its operand.

[Note 1: The value obtained is a copy of the original value. — end note]

The operand shall be a modifiable lvalue. ... The value of the operand object is modified (defns.access) by adding 1 to it. The value computation of the ++ expression is sequenced before the modification of the operand object. ...

2 The operand of postfix -- is decremented analogously to the postfix ++ operator.

7.6.1.6 Increment and decrement - expr.post.incr

The equivalent section in the C-Standard is 6.5.2.4 Postfix increment and decrement operators

Let me know if you have any further questions.

Upvotes: 5

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