C# IEnumerable and string[]

Question

i searched for a method to split strings and i found one.
Now my problem is that i can´t use the method like it is described.

Stackoverflow answer

It is going to tell that i

cannot implicitly convert type 'System.Collections.Generic.IEnumerable' to 'string[]'.

The provided method is:

public static class EnumerableEx
{
    public static IEnumerable<string> SplitBy(this string str, int chunkLength)
    {
        if (String.IsNullOrEmpty(str)) throw new ArgumentException();
        if (chunkLength < 1) throw new ArgumentException();

        for (int i = 0; i < str.Length; i += chunkLength)
        {
            if (chunkLength + i > str.Length)
                chunkLength = str.Length - i;

            yield return str.Substring(i, chunkLength);
        }
    }
}

How he said it is used:

string[] result = "bobjoecat".SplitBy(3); // [bob, joe, cat]

@AmitKumarGhosh You can assign a `string[]` to an `IEnumerable` The problem is the opposite: you cannot assign an `IEnumerable` to a `string[]` — Dennis_E, Jun 23 '15 at 10:16
@AmitKumarGhosh, [Arrays do implement IEnumerable](https://ideone.com/d8rBt6), since .NET Framework 2.0, but only at [run-time](https://msdn.microsoft.com/en-us/library/system.array.aspx#remarksToggle). However, as mentioned by Dennis_E, this is not the root of the problem. — awesoon, Jun 23 '15 at 10:20
@soon: it's also [documented](https://msdn.microsoft.com/en-us/library/system.array.aspx): _"Starting with the .NET Framework 2.0, the Array class implements the System.Collections.Generic.IList, System.Collections.Generic.ICollection, and System.Collections.Generic.IEnumerable generic interfaces. The implementations are provided to arrays at run time..."_ — Tim Schmelter, Jun 23 '15 at 10:36
Sure, and my comment has the same link under `run-time` words. — awesoon, Jun 23 '15 at 10:40

score 8 · Accepted Answer · answered Jun 23 '15 at 10:07

8

You have to use ToArray() method:

string[] result = "bobjoecat".SplitBy(3).ToArray(); // [bob, joe, cat]

You can implicitly convert Array to IEnumerable but cannot do it vice versa.

answered Jun 23 '15 at 10:07

kamil-mrzyglod

4,948
1
20
29

I tried now for over 2 Hours and never thought that its so Simple. Thank you very much! – Chakratos Jun 23 '15 at 10:10
@Chakratos - glad it helped! – kamil-mrzyglod Jun 23 '15 at 10:11

score 1 · Answer 2 · answered Jun 23 '15 at 10:48

Note that you could even modify directly the method to return a string[]:

public static class EnumerableEx
{
    public static string[] SplitByToArray(this string str, int chunkLength)
    {
        if (String.IsNullOrEmpty(str)) throw new ArgumentException();
        if (chunkLength < 1) throw new ArgumentException();

        var arr = new string[(str.Length + chunkLength - 1) / chunkLength];

        for (int i = 0, j = 0; i < str.Length; i += chunkLength, j++)
        {
            if (chunkLength + i > str.Length)
                chunkLength = str.Length - i;

            arr[j] = str.Substring(i, chunkLength);
        }

        return arr;
    }
}

score 0 · Answer 3 · answered Sep 05 '18 at 12:56

0

If somehow you end up with this: IEnumerable<string> things = new[] { "bob", "joe", "cat" }; you can transform it into string[] like this: string[] myStringArray = things.Select(it => it).ToArray();

answered Sep 05 '18 at 12:56

Gabriel Marius Popescu

2,016
2
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C# IEnumerable and string[]

3 Answers3