使用C#var隐式键入System.Data.Datarow [英] Use of C# var for implicit typing of System.Data.Datarow

问题描述

foreach (var row in table.Rows)
{
     DoSomethingWith(row);
}

假设我正在使用标准的System.Data.DataTable(具有System.Data.DataRow对象的集合)，则上面的变量'row'解析为object类型，而不是System.Data.DataRow.

Assuming that I'm working with a standard System.Data.DataTable (which has a collection of System.Data.DataRow objects), the variable 'row' above resolves as an object type, not a System.Data.DataRow.

foreach (DataRow row in table.Rows)
{
     DoSomethingWith(row);
}

符合我的期望.有什么特殊原因吗?

Works as I would expect. Is there a particular reason for this?

谢谢.

推荐答案

这是因为Rows是DataRowCollection，这又是IEnumerable而不是IEnumerable<DataRow>，这意味着推断的类型将是object

That's because Rows is DataRowCollection, which in turn is IEnumerable and not IEnumerable<DataRow>, which means that type inferred will be object.

当您明确声明foreach中的类型时，您会指示c#将强制类型转换添加到每个调用中，这就是它起作用的原因.

When you explicitly state type in foreach, you instruct c# to add cast to each call, which is why it works.

这篇关于使用C#var隐式键入System.Data.Datarow的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！