C# IEnumerable<string> 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]

Answer 1

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.

Answer 2

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;
    }
}

Answer 3

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();