Re: [Boost-users] Problems using for_each

Hello, On Sun, Mar 31, 2013 at 12:20 PM, Michael Powell wrote:

On Sun, Mar 31, 2013 at 12:08 PM, Will Mason wrote:

...

Hello,

On Sun, Mar 31, 2013 at 10:56 AM, Michael Powell wrote:

...

Hello,

I am struggling making for_each work right. I am using Sourcery targeting ARM. AFAIK, GCC is actually 4.7.2, and I am flagging -std=c++11.

I'm not really picky how we get for_each done (or constructs like it). I'd like to avoid "macro-expansion" for obvious reasons (i.e. debug), and the always-infamous verbosity of a for loop, if possible.

I've got the following:

vector all; rgb_type rgb; rgb_type rgb2 = rgb.clone();

for_each(all.begin(), all.end(), cout << _1->r() << endl);

Since you are using gcc 4.7.2 with -std=c++11, you can just use a std lambda here:

std::for_each(all.begin(), all.end(), [] (rgb_type* val) { std::cout << val->r() << std::endl; });

Yessir, I believe that will work. Possibly also std::bind as needs be.

A little refresher for me, []: return value (void implied), (): captured function args (with in/out/inout rules), {}: lambda body.

Also, it occurs to me that, depending on your personal stylistic preferences, you could do the following with about the same level of verbosity: for (auto val : all) std::cout << val->r() << std::endl; Cheers, Will

I think what I am also finding is Sourcery code highlighting, so-called "Semantic Errors" isn't quite in alignment with current C++ language standards.

Thank ye.

...

Cheers, Will

...

With errors:

_1 was not declared in this scope. (C++ Problem)

That or,

void rgb_printer_func(rgb_type* prgb) { cout << prgb->r() << endl; }

for_each(all.begin(), all.end(), rgb_printer_func);

With errors:

Invalid arguments Candidates are: #1 for_each(#0, #0, #1) (Semantic

Error)

...

Thank you.

Regards,

Michael Powell _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

---

Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users