Question

我有一个List<CreditCard>，信用卡的属性是CreditCardNumber，这是一个字符串。不幸的是，它们可以是1234 1234 1234 1234或1234123412341234，它们都是相同的数字。

我需要检查并删除这些重复的项目。有人可以帮忙吗？

Answer 1

using System.Linq;

public List<string> GetUniqueCardNumbers(List<string> cardNumbers)
{
    // First replace the spaces with empty strings
    return cardNumbers.Select(cc => cc.Replace(" ", ""))
                      .Distinct()
                      .ToList();
}

Answer 2

最佳选择是在输入时从卡号中删除空格，这样您只需执行一次清洁操作：

    public class CreditCard: IComparable<CreditCard>
    {
        string creditCardNumberClean;
        string creditCardNumberOriginal;
        public string CreditCardNumber
        {
            get 
            { 
                return this.creditCardNumberOriginal; 
            }
            set
            {
                this.creditCardNumberOriginal = value;
                this.creditCardNumberClean = value.Replace(" ", "");
            }
        }
        public CreditCard(string creditCardNumber)
        {
            this.CreditCardNumber = creditCardNumber;
        }

        public int CompareTo(CreditCard other)
        {
            return this.creditCardNumberClean.CompareTo(other.creditCardNumberClean);
        }
    }

但如果那是不可能的话，你基本上想要在卡号上执行字符串比较，只是改变数字以在比较之前删除所有空格：

    class Program
    {
        public static void Main(string[] args) 
        {
            List<string> list = new List<string>(new string[]{"1234 1234 1234 1234", "1234123412341234","9999 9999 9999 9999"});
            SortedSet<string> set = new SortedSet<string>(list, new CreditCardNoComparer());
            foreach (string s in set)
            {
                Console.WriteLine(s);
            }
            Console.ReadKey();
        }
    }
    public class CreditCardNoComparer : IComparer<string>
    {
        public int Compare(string x, string y)
        {
            return x.Replace(" ", "").CompareTo(y.Replace(" ", ""));
        }

    }

修改

//version using overridden GetHashCode and Equals methods as per @lazyberezovsky's comments public class CreditCard { long creditCardNumberClean; //given the card number is numeric this is the most efficient way of storing it string creditCardNumberOriginal; public string CreditCardNumber { get { return this.creditCardNumberOriginal; } set { this.creditCardNumberOriginal = value; this.creditCardNumberClean = long.Parse(value.Replace(" ", "")); } } public CreditCard(string creditCardNumber) { this.CreditCardNumber = creditCardNumber; } public override bool Equals(object obj) { CreditCard other = obj as CreditCard; return other == null ? false : this.creditCardNumberClean.Equals(other.creditCardNumberClean); } public override int GetHashCode() { return this.creditCardNumberClean.GetHashCode(); } }

Answer 3

从每个
使用Distinct();

Answer 4

您可以为EqualityComparer创建自己的CreditCard，删除空格并使用Enumerable.Distinct删除重复项：

public class CardComparer : IEqualityComparer<CreditCard>
{
    private readonly Regex re = new Regex(@"\s+");

    public bool Equals(CreditCard x, CreditCard y)
    {
        return re.Replace(x.Number, "") == re.Replace(y.Number, "");
    }

    public int GetHashCode(CreditCard obj)
    {
        return re.Replace(obj.Number, "").GetHashCode();
    }
}

然后：

IEnumerable<CreditCard> unique = sourceList.Distinct(new CardComparer());

Answer 5

首先，您必须确定什么构成“平等”。如果它像删除嵌入空格一样简单，那么您可以使用以前的解决方案之一来删除空格并调用Distinct。否则，您必须创建一个相等比较器并将其传递给Distinct overload。

Answer 6

IEnumerable<CreditCard> distinctCards = cards
  .Select(card => new {
     card, 
     ccn = card.CreditCardNumber.Replace(" ", string.Empty)
  })
  .GroupBy(x => x.ccn)
  .Select(g => g.First().card) //group has at least 1 member, so First() is safe
  //.ToList()   ???

Answer 7

您只能从任何字符串中提取数字，在这种情况下，您只能替换空字符的空格字符，对于更复杂的字符串格式，您可以使用下一个代码仅获取数字。您可以查看以下答案：get only digits

string justNumbers = new String("asd123 f3 4.34-3 ".Where(Char.IsDigit).ToArray());

然后您将只拥有CreditCardNumber的数字，并且可以搜索重复的值。

我需要从List＆lt;＆gt;中删除重复项

7 个答案: