Ian Mercer posted a similar solution as this on Phil Haack's blog:
foreach (var item in Model.Select((value, i) => new { i, value }))
{
var value = item.value;
var index = item.i;
}
This gets you the item (item.value
) and its index (item.i
) by using this overload of LINQ's Select
:
the second parameter of the function [inside Select] represents the index of the source element.
The new { i, value }
is creating a new anonymous object.
Heap allocations can be avoided by using ValueTuple
if you're using C# 7.0 or later:
foreach (var item in Model.Select((value, i) => ( value, i )))
{
var value = item.value;
var index = item.i;
}
You can also eliminate the item.
by using automatic destructuring:
<ol>
foreach ((MyType value, Int32 i) in Model.Select((value, i) => ( value, i )))
{
<li id="item_@i">@value</li>
}
</ol>
for (Iterator<String> i = someIterable.iterator(); i.hasNext();) {
String item = i.next();
System.out.println(item);
}
Note that if you need to use i.remove();
in your loop, or access the actual iterator in some way, you cannot use the for ( : )
idiom, since the actual iterator is merely inferred.
As was noted by Denis Bueno, this code works for any object that implements the Iterable
interface.
Also, if the right-hand side of the for (:)
idiom is an array
rather than an Iterable
object, the internal code uses an int index counter and checks against array.length
instead. See the Java Language Specification.
Best Answer
https://golang.org/ref/spec#For_range
As an example:
If you don't care about the index, you can use
_
:The underscore,
_
, is the blank identifier, an anonymous placeholder.