[英]C# Comparing Two Custom Lists
我遇到了一种情况,我需要将两个不同的列表相互比较,我想知道这样做的最佳方法是什么? 我以为这样的事情会起作用,但不会,而且我不知道为什么。 Linq查询正在返回它不应该返回的记录。 这是我第一次尝试找出类似的内容,因此毫无疑问是凌乱的。
private static List<ColumnDefinition> FindTableStructureUpdates(List<ColumnDefinition> colDefs, List<ColumnDefinition> tblCols)
{
List<ColumnDefinition> ColsToUpdate = new List<ColumnDefinition>();
for (int i = 0; i < colDefs.Count; ++i)
{
string colDefName = colDefs[i].ColName;
string colDefDataType = colDefs[i].ColType;
string colDefAttribute = colDefs[i].ColAttributes;
var query = from tbl in tblCols
where tbl.ColName != colDefName && tbl.ColType != colDefDataType && tbl.ColAttributes != colDefAttribute
select new { colDefName, colDefDataType, colDefAttribute };
if (query.Count() > 0)
{
foreach (var item in query)
{
ColsToUpdate.Add(new ColumnDefinition(item.colDefName, item.colDefDataType, item.colDefAttribute));
}
}
}
return ColsToUpdate;
任何建议都很好。
谢谢。
IEquatable实现?
#region IEquatable<ColumnDefinition> Members
public bool Equals(ColumnDefinition other)
{
if (this.ColName.Equals(other.ColName) && this.ColType.Equals(other.ColType) && this.ColAttributes.Equals(other.ColAttributes))
return true;
return false;
}
您不能使用Enumerable.Except
吗?
public static IEnumerable<TSource> Except<TSource>( this IEnumerable<TSource> first, IEnumerable<TSource> second )
更多细节 。
在Snippet编译器中测试的示例
using System;
using System.Linq;
using System.Collections.Generic;
class ColumnDefinition : IEquatable<ColumnDefinition>
{
public string Name { get; set; }
public string Type { get; set; }
public string Attr { get; set; }
public ColumnDefinition()
{
Name = string.Empty;
Type = string.Empty;
Attr = string.Empty;
}
public bool Equals(ColumnDefinition other)
{
return Name.Equals(other.Name) && Type.Equals(other.Type) && Attr.Equals(other.Attr);
}
public override bool Equals(object value)
{
return (value is ColumnDefinition) ? Equals(value as ColumnDefinition) : false;
}
public override int GetHashCode()
{
return Name.GetHashCode() ^ Type.GetHashCode() ^ Attr.GetHashCode();
}
public override string ToString()
{
return string.Concat("{", Name, ":", Type, ":", Attr, "}");
}
}
public class Program
{
public static void Main(string[] args)
{
try
{
MyMain(args);
}
catch (Exception e)
{
Console.WriteLine(e);
}
finally
{
Console.ReadKey();
}
}
public static void MyMain(string[] args)
{
var list1 = new []
{
new ColumnDefinition { Name = "foo", Type = "int", Attr = "0" },
new ColumnDefinition { Name = "bar", Type = "int", Attr = "1" },
};
var list2 = new []
{
new ColumnDefinition { Name = "foo", Type = "int", Attr = "0" },
new ColumnDefinition { Name = "bar", Type = "string", Attr = "1" },
};
foreach (var changed in Enumerable.Except(list1, list2))
{
Console.WriteLine(changed);
}
}
}
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