题
我看到IndexOf()
使用List<T>
方法的所有实施例是基本串类型的。我想知道是怎么回事这是一个对象列表类型的索引,基于对象变量之一。
List<Employee> employeeList = new List<Employee>();
employeeList.Add(new Employee("First","Last",45.00));
我想找到的索引,其中employeeList.LastName == "Something"
解决方案
int index = employeeList.FindIndex(employee => employee.LastName.Equals(somename, StringComparison.Ordinal));
编辑:如果没有为C#2.0的lambda(原不使用LINQ或任何.NET 3+特征,只是在C#3.0拉姆达语法):
int index = employeeList.FindIndex(
delegate(Employee employee)
{
return employee.LastName.Equals(somename, StringComparison.Ordinal);
});
其他提示
public int FindIndex(Predicate<T> match);
使用lambda表达式:
employeeList.FindIndex(r => r.LastName.Equals("Something"));
注意:
// Returns:
// The zero-based index of the first occurrence of an element
// that matches the conditions defined by match, if found;
// otherwise, –1.
可以通过手柄做此equals方法
class Employee
{
string _name;
string _last;
double _val;
public Employee(string name, string last, double val)
{
_name = name;
_last = last;
_val = val;
}
public override bool Equals(object obj)
{
Employee e = obj as Employee;
return e._name == _name;
}
}
对不起,一个更良好的措施:)
int index = employees.FindIndex(
delegate(Employee employee)
{
return employee.LastName == "Something";
});
修改: - 在.NET 2.0项目全部实施例
class Program
{
class Employee { public string LastName { get; set; } }
static void Main(string[] args)
{
List<Employee> employeeList = new List<Employee>();
employeeList.Add(new Employee(){LastName="Something"});
employeeList.Add(new Employee(){LastName="Something Else"});
int index = employeeList.FindIndex(delegate(Employee employee)
{ return employee.LastName.Equals("Something"); });
Console.WriteLine("Index:{0}", index);
Console.ReadKey();
}
}
我更喜欢这样
private List<Person> persons = List<Person>();
public PersonService()
{
persons = new List<Person>() {
new Person { Id = 1, DOB = DateTime.Today, FirstName = "Pawan", LastName = "Shakya" },
new Person { Id = 2, DOB = DateTime.Today, FirstName = "Bibek", LastName = "Pandey" },
new Person { Id = 3, DOB = DateTime.Today, FirstName = "Shrestha", LastName = "Prami" },
new Person { Id = 4, DOB = DateTime.Today, FirstName = "Monika", LastName = "Pandey" },
};
}
public PersonRepository.Interface.Person GetPerson(string lastName)
{
return persons[persons.FindIndex(p=>p.LastName.Equals(lastName, StringComparison.OrdinalIgnoreCase))];
}
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