什么是默认值KeyValuePair<string, int>
?
例如,我正在运行LINQ查询并FirstOrDefault()
从中返回值
KeyValuePair<string, int> mapping = (from p in lstMappings
where p.Key.Equals(dc.ColumnName, StringComparison.InvariantCultureIgnoreCase)
select p).FirstOrDefault();
if (mapping != null)
{
}
如何检查mapping
对象是否为空/空白
(我在上面的代码中得到编译时错误Operator '!=' cannot be applied to operands of type 'System.Collections.Generic.KeyValuePair<string,int>' and '<null>'
)
PS:lstMappings
是类型的
List<KeyValuePair<string, int>>
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