c# - C# 列表

Question

I would like to initialize a list with a given number of items, all with value DBNull.Value, is this possible via AddRange?

This code initializes as nulls and not DBNull.Value

_cellList = new List<object>(new DBNull[_columns.Count]);

Whereas this does the job correctly, but with a for loop:

_cellList = new List<object>();
for(int i = 0; i<_columns.Count; i++)
{
    _cellList.Add(DBNull.Value);
}

thanks

score 3 · Accepted Answer

您可以Enumerable.Repeat与结合使用ToList，如下所示：

_cellList = Enumerable
    .Repeat(DBNull.Value, _columns.Count)
    .Cast<object>()
    .ToList();

请注意使用Cast<object>()，这是构造List<object>而不是所必需的List<DBNull>。

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