Le Wed, 06 Nov 2013, Matej Kosik a écrit :

> Hi,
> 
> I would like to ask, how to do something like:
> 
> 	let computed_format = Printf.sprintf "%%0%dd" 5 in
> 	Printf.printf computed_format 42
> 
> The above code is rejected, because "computed_format" is of type "string" whereas
> 
>         ('a -> 'b, out_channel, unit) format =
>            ('a -> 'b, out_channel, unit, unit, unit, unit) format6
> 
> type was expected.
> 
> My question is: is it possible to turn strings to values that would be accepted by Printf.printf as its first parameter?

I don't think you can in general, because format strings are typed (so
that the compiler can check the correctness of Printf.printf calls).

However, you could try something along

let computed_format = Printf.sprintf "%%0%d%d" 5 in
print_string (computed_format 42)

-- 
Simon