How to initialize List<> with array? Like:
List<string> list = new List<string>();
string[] str = new string[5];
list = str;
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1That is not initialisation, that is assignment. That might seem pedantic, but the difference is very important in programmingColin Grealy– Colin Grealy2015-12-06 21:04:45 +00:00Commented Dec 6, 2015 at 21:04
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3 Answers
There is a constructor of List which takes an IEnumerable (which an array implements)
string[] myArray = new string[5];
List<string> myList = new List<string>(myArray);
https://msdn.microsoft.com/en-us/library/fkbw11z0(v=vs.100).aspx
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Pass the array to the List constructor
List<string> list = new List<string>(str);
or use ToList() extension method
List<string> list = str.ToList();
Both of these will create a new List<string> containing elements copied from str.
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Another form, which can only be used if you are declaring the 'array' elements at the same time that you are initializing the list, would be using the collection initializer.
Strictly speaking this does not use an existing array to initialize the list. But in some situations, this would be an advantage, i.e. you don't have to also declare, nor allocate memory, for a separate array variable.
I personally like this form because of its conciseness.
// several examples (note: no separate array is declared during initialization
// of the list)
List<int> digits = new List<int> { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
List<Cat> cats = new List<Cat>
{
new Cat{ Name = "Sylvester", Age=8 },
new Cat{ Name = "Whiskers", Age=2 }
};
List<Cat?> moreCats = new List<Cat?>
{
new Cat{ Name = "Peaches", Age=4 },
null
};
var numbers = new Dictionary<int, string>
{
[7] = "seven",
[9] = "nine",
};
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