Hi, I am learning how to use readf to read integers. I follow the example in  https://dlang.org/library/std/stdio/readf.html

The sample code use readf in following way
readf!" %d"(a);

It works when I use dmd 2.074. However, I got compile error when I switch to ldc2
/usr/include/d/std/stdio.d(3339): Error: tuple A is used as a type
b.d(8): Error: template instance std.stdio.readf!" %d" error instantiating

It turns out that I can compile the code using ldc2 if I change the line to
readf(" %d", &a);

So my questions are
1. Should I use ampersand? I search the web and other people use ampersand. But from the doc I guess that I can also pass arguments as ref and do need to use ampersand?

2. I also tried changing the code to readf!" %d"(&a); and ldc2 gives me the same error. I search and the ! does something called template instantiation. Why it does not work here?

Thanks for your help!

On 05/28/2017 07:55 AM, Petras wrote:
> Hi, I am learning how to use readf to read integers. I follow the
> example in  https://dlang.org/library/std/stdio/readf.html
>
> The sample code use readf in following way
> readf!" %d"(a);

Providing the format string as a template argument and being able to pass references are both 2.074 features.

> It turns out that I can compile the code using ldc2 if I change the line to
> readf(" %d", &a);

That's the old way that should work with 2.074 as well.

Ali

On Sunday, 28 May 2017 at 15:00:30 UTC, Ali Çehreli wrote:
> On 05/28/2017 07:55 AM, Petras wrote:
> > Hi, I am learning how to use readf to read integers. I follow
> the
> > example in  https://dlang.org/library/std/stdio/readf.html
> >
> > The sample code use readf in following way
> > readf!" %d"(a);
>
> Providing the format string as a template argument and being able to pass references are both 2.074 features.
>
> > It turns out that I can compile the code using ldc2 if I
> change the line to
> > readf(" %d", &a);
>
> That's the old way that should work with 2.074 as well.
>
> Ali

Thanks!