Question

如何将var类型转换/转换为List类型？

此代码段给出了错误：

List<Student> studentCollection = Student.Get();

var selected = from s in studentCollection
                           select s;

List<Student> selectedCollection = (List<Student>)selected;
foreach (Student s in selectedCollection)
{
    s.Show();
}

Answer 1

当您执行Linq to Objects查询时，它会返回IEnumerable<Student>类型，您可以使用ToList()方法从List<T>创建IEnumerable<T>：

var selected = from s in studentCollection
                           select s;

List<Student> selectedCollection = selected.ToList();

Answer 2

示例代码中的var实际上是IEnumerable<Student>。 如果您要做的就是枚举它，则无需将其转换为列表：

var selected = from s in studentCollection select s;

foreach (Student s in selected)
{
    s.Show();
}

如果确实需要它作为列表，Linq的ToList()方法会将其转换为一个。

Answer 3

您可以调用ToList LINQ扩展方法

List<Student> selectedCollection = selected.ToList<Student>();
foreach (Student s in selectedCollection)
{
    s.Show();
}

Answer 4

尝试以下

List<Student> selectedCollection = selected.ToList();

C＃ - var to List <t>转换</t>

4 个答案: