【C#】判断list集合中是否存在相同项

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新建Student测试

public class Student
{
    public int ID { get; set; }
    public string Name { get; set; }
}

创建一个list

List<Student> list = new List<Student>();

添加数据

list.Add(new Student() { ID = 1, Name = "Jack" });
list.Add(new Student() { ID = 2, Name = "Jane" });
list.Add(new Student() { ID = 2, Name = "Mary" });

现在，判断Name是否重复

用双重for循环

private bool IsRepeat()
{
    for (int i = 0; i < list.Count; i++)
    {
        for (int j = i + 1; j < list.Count; j++)
        {
            if (list[i].Name == list[j].Name)
            {
                return true;
            }
        }
    }
    return false;
}

用Linq

bool isRepeat = list.GroupBy(i => i.Name).Where(g => g.Count() > 1).Count() > 0;

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