On Thursday, 4 July 2013 at 06:18:21 UTC, CJS wrote:
I'm having trouble understanding the difference between casting
and std.conv.to. Any help?
Casting merely changes the "observed type", whereas "to" does a
deep conversion.
Observe:
----
import std.stdio;
import std.conv;
void main()
{
int[] ints = [1, 2, 3];
auto bytes1 = cast(ubyte[])(ints);
auto bytes2 = to!(ubyte[])(ints);
writeln(bytes1);
writeln(bytes2);
}
----
[1, 0, 0, 0, 2, 0, 0, 0, 3, 0, 0, 0]
[1, 2, 3]
----
To is very useful to do "true" type conversion. It can change
string width. Finally, "to" is able to do string interpretation.
EG:
----
import std.stdio;
import std.conv;
void main()
{
int[] ints = to!(int[])("[1, 2, 3]");
writeln(ints);
}
----
[1, 2, 3]
----
To is very convenient because it is a "one stop shop": It doesn't
matter what you want to do: "to" will do it. You don't need to
mix/match calls to atoi/itoa/encode/decode etc. Furthermore, it
is safe: if anything fails, to will throw. It will also throw if
you overflow:
----
import std.conv;
void main()
{
int a = 500;
ubyte b = cast(ubyte)(a); //No problem here: Silent overflow
ubyte c = to!ubyte(a); //Runtime overflow exception
}
----
Hope that helps :)
