What does the >?= operator mean?

Question

Looking through this C++ BigInt library and found the BigInt.cpp file. At the top there is a a comment at the top about compatibility:

This class was written for the g++ compiler and uses some of the g++ extensions (like "long double" and the ">?=" operator).

What does that >?= operator do? I can't find a reference to it anywhere else.

long double is not a g++ extension... – Johannes Schaub - litb Mar 04 '11 at 21:53 — Johannes Schaub - litb, Mar 04 '11 at 21:53

score 52 · Accepted Answer · edited May 15 '11 at 05:09

52

It's a GCC extension that was removed in GCC version 4.2 and later.

The equivalent of a >?= b is a = max(a,b);

There is also a very similar operator a <?= b which means the same as a = min(a, b);.

edited May 15 '11 at 05:09

Omnifarious

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answered Mar 04 '11 at 21:50

Thomas Jones-Low

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score 14 · Answer 2 · answered Mar 04 '11 at 21:50

14

This page describes that >? is the 'maximum' operator, which returns the largest of its two numeric arguments. I'm guessing that the >?= combines this with assignment, presumably by assigning to the left-hand operand if the right-hand value is larger.

answered Mar 04 '11 at 21:50

Tim Martin

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tim, sounds plausable - and very likely, therefore, +1 :) – jim tollan Mar 04 '11 at 21:51
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It kinda makes sense that they'd use `>?` for the maximum operator, seeing that the maximum can be computed in regular C++ like this: `max = lhs > rhs ? lhs : rhs`. – Emile Cormier Mar 04 '11 at 21:52
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Compiler specific language extensions?! I thought only MS were dumb enough to do that. Boo! Hiss! – David Heffernan Mar 04 '11 at 21:52
I went to test it, but as reported elsewhere it's been removed in more recent versions of g++. – Tim Martin Mar 04 '11 at 21:53
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@David: There's also `__attribute__`. But of course some extensions are more obnoxious than others. – aschepler Mar 04 '11 at 21:57
As long as there's a compiler switch to compile in a fully standards-compliant mode, I'm happy. Bonus points if standards-compliant is the default. – Tim Martin Mar 04 '11 at 21:58
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`>?=` is really quite disgusting though! – David Heffernan Mar 04 '11 at 21:58
Out of interest, were you able to overload these operators? – Bathsheba May 12 '16 at 05:32

score 3 · Answer 3 · edited May 23 '17 at 12:10

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See C extension: <? and >? operators

It's the max-then-assign operator: Take the greater of the left and right sides and stuff it back into the lefthand side.

It's removed from g++ and should be replaced with max (or min for <?=)

edited May 23 '17 at 12:10

Community

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answered Mar 04 '11 at 21:52

Mark B

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What does the >?= operator mean?

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