foreach with index

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How do you get the index of the current iteration of a foreach loop? 31 answers

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I keep this extension method around for this:

public static void Each<T>( this IEnumerable<T> ie, Action<T, int> action )
{
    var i = 0;
    foreach ( var e in ie ) action( e, i++ );
}

And use it like so:

var strings = new List<string>();
strings.Each( ( str, n ) =>
{
    // hooray
} );

Or to allow for break -like behaviour:

public static bool Each<T>( this IEnumerable<T> ie, Func<T, int, bool> action )
{
    int i = 0;
    foreach ( T e in ie ) if( !action( e, i++ ) ) return false;
    return true;
}

var strings = new List<string>() { "a", "b", "c" };
bool iteratedAll = strings.Each( (str, n) ) =>
{
    if( str == "b" ) return false;
    return true;
} );

---

You can do the following

foreach ( var it in someCollection.Select((x,i) => new { Value = x, Index=i }) )
{
   if ( it.Index > SomeNumber) //      
}

This will create an anonymous type value for every entry in the collect. It will have two properties

Value: with the original value in the collection

Index: with the index within the collection

---

The C# foreach doesn't have a built in index. You'll need to add an integer outside the foreach loop and increment it each time.

int i = -1;
foreach (Widget w in widgets)
{
   i++;
   // do something
}

Alternatively, you could use a standard for loop as follows:

for (int i = 0; i < widgets.Length; i++)
{
   w = widgets[i];
   // do something
}

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