auto w = unsigned long{23};

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Hi! I got a C++11 newbie question. The following works as expected ...

auto w = long{23};

... but if I try this ...

auto w = unsigned long{23};

... gcc says ...

expected primary-expression before 'unsigned'

What's the correct C++11'ish way to solve this?

Chris Kawa

Sounds like a bug in gcc. Works ok in MSVC. There are couple of ways to fix it:

A (non-standard, borrowed from C) workaround that seems to work on gcc (but correctly fails in MSVC) is:

auto w = (unsigned long){23};

But don't use that. Seriously :) The standard compliant workaround is a using declaration (or a typedef if you prefer):

using ulong = unsigned long;
auto w = ulong{23};

But honestly, for simple types just do this:

auto w = 23ul;

or this if you really want uniform syntax:

auto w{23ul};

EDIT: Some people claim that it's in fact MSVC that is in error and it's not a correct syntax. You'd better look it up in the standard if you want to know for sure. To me it's too obscure to bother :P

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@Chris-Kawa Thank you for your reply and for testing it with MSVC. Interesting you think this might be a gcc bug; I always refrain from blaming the compiler because when something went wrong in the past in the end it was all my fault every single time. :) Also thanks for your workaround suggestions. The using-workaround is what I use by now.

Edit: Thanks for the link. Yes, it's obscure.

SGaist

Hi,

gcc's not alone. My old OS X clang isn't happy either with it.