覆盖 .ToString 方法 c#

Override .ToString method c#

提问by Zoro

Okay, so I wrote this program out of the exercise of a C# programming book (I'm trying to learn here) and it asks for "Override the ToString() method to return all data members".

好的，所以我根据一本 C# 编程书的练习编写了这个程序（我正在尝试在这里学习），它要求“覆盖 ToString() 方法以返回所有数据成员”。

Have I done this correctly? Or have I just successfully wrote code that compiles but does nothing. What is the purpose of ToString?

我做对了吗？或者我刚刚成功编写了可以编译但什么都不做的代码。ToString的目的是什么？

I have spent about 30 minutes looking at other posts on this and havn't figured it out, So I decided to make this.

我花了大约 30 分钟查看有关此的其他帖子，但还没有弄清楚，所以我决定做这个。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication297
{
class Program
{
    static void Main(string[] args)
    {
        String name = "Stormtrooper";
        Employee s = new Employee(name);
        Console.WriteLine("The type of hire is a {0}", s.Name);
        Console.WriteLine("The identification number is {0}", s.Number);
        Console.WriteLine("The date of hire is {0} ABY", s.Date);
        Console.WriteLine("The standard galactic salary is...{0:C}", s.Salary);

    }

    class Employee
    {
        private string _name;
        private string _number;
        private int _date;
        private int _salary;
        public string Name
        {
            get
            {
                return _name;
            }
        }

        public string Number
        {
            get
            {
                return _number;
            }
        }

        public int Date
        {
            get
            {
                return _date;
            }
        }
        public int Salary
        {
            get
            {
                return _salary;
            }
        }
        public Employee(string n)
        {
            _name = n;
            _number = "AA23TK421";
            _date = 4;
            _salary = 800;
        }
    }

    public override string ToString()

    {
        return "_name + _number + _date + _salary".ToString();
    }
}
}

采纳答案by Scott Chamberlain

You are returning a string that just says the phrase _name + _number + _date + _salary.

您正在返回一个只显示短语的字符串_name + _number + _date + _salary。

What you likely wanted to do is build a string using those fields. If you wanted them all mushed together Concatwould work, but it would be highly un-readable

您可能想要做的是使用这些字段构建一个字符串。如果您希望将它们全部混合在一起，则Concat可以工作，但会非常不可读

public override string ToString()
{
    return String.Concat(_name, _number, _date, _salary);
}

However what would be better is to use Formatand include labels with the values

但是，更好的是使用Format并包含带有值的标签

public override string ToString()
{
    return String.Format("Name:{0}, Number:{1}, Date:{2}, Salary:{3}",_name, _number, _date, _salary);
}

---

---

If you are using C# 6 or newer you can use the following cleaner format

如果您使用的是 C# 6 或更新版本，您可以使用以下更简洁的格式

public override string ToString()
{
    return $"Name:{_name}, Number:{_number}, Date:{_date}, Salary:{_salary}";
}

Which is the exact same logic as the previous String.Formatversion.

这与以前的String.Format版本完全相同的逻辑。

回答by Adriaan Stander

Rather try something like

而是尝试类似的东西

public override string ToString()
{
    return String.Format("Name : {0}, number {1}, date {2}, salary {3}",_name,_number,_date,_salary);
}

But it neads to be part of the class

但它需要成为课堂的一部分

so

所以

class Employee
{
    private string _name;
    private string _number;
    private int _date;
    private int _salary;

    .....

    public override string ToString()
    {
        return String.Format("Name : {0}, number {1}, date {2}, salary {3}",_name,_number,_date,_salary);
    }
}

Have a look at String.Format Method

看看String.Format 方法

Replaces each format item in a specified string with the text equivalent of a corresponding object's value.

用对应对象值的文本替换指定字符串中的每个格式项。

回答by Rex

You could try to format the output in a nice format. (not tested, though)

您可以尝试以良好的格式格式化输出。（虽然没有测试）

public override string ToString()
{
    return string.Format("Name: {0} Number: {1:n0} Date: {2:yyyy-MM-dd} Salary: {3:n2}", _name, _number, _date, _salary);
}

there are a lot of purposes overwriting .ToString(), depending on the context. for example,

根据上下文，有很多目的可以覆盖 .ToString()。例如，

• some developers like to have nicely formatted object description when doing debug, overwriting .ToString() would allow them to have meaningful description with some identifier (for example, the Id of a object);
• Some developers like to put some serialization code into the ToString() method;
• Some developers even put some debug code into the .ToString() method, though it might not be a good practice.

• 一些开发人员喜欢在调试时使用格式良好的对象描述，覆盖 .ToString() 将允许他们使用某些标识符（例如，对象的 Id）进行有意义的描述；
• 有些开发者喜欢在 ToString() 方法中放入一些序列化代码；
• 一些开发人员甚至将一些调试代码放入 .ToString() 方法中，尽管这可能不是一个好的做法。

it really depending on the context of your needs. you may find some good practices to follow online - believe there are plenty of resources online.

这真的取决于您的需求。您可能会在网上找到一些好的做法 - 相信网上有很多资源。

回答by Karl Anderson

The reason people override the ToString()method is to have a default string representation of your object, usually for display to the user or in a log or console, like this:

人们重写该ToString()方法的原因是拥有对象的默认字符串表示形式，通常用于显示给用户或在日志或控制台中，如下所示：

Console.WriteLine(yourClassObject);

If you do not override the ToString(), then its default implementation is to return the fully qualified name of your object, like this:

如果不覆盖ToString()，则其默认实现是返回对象的完全限定名称，如下所示：

YourNamespace.YourClassName

By changing the inherited implementation (from System.Object), then you can make a nicer (read: prettier) representation, like this:

通过更改继承的实现（来自System.Object），您可以制作更好（阅读：更漂亮）的表示，如下所示：

public override string ToString()
{
    return String.Format("This instance of my object has the following: Name = {0}, Number = {1}, Date = {2}, Salary = ", _name, _number, _date, _salary);
}

回答by bytedev

If you are using C# 6 (or later) use the nameof()method for the property names in the string in case the propery names change. You can also use the $""notation instead of using string.Format().

如果您使用的是 C# 6（或更高版本），请使用nameof()字符串中的属性名称的方法，以防属性名称更改。您也可以使用$""符号代替 string.Format()。

For example:

例如：

public override string ToString()
{
    return $"{nameof(Name)}: {_name}";
}

回答by Guy

Without overiding ToString, if you tried to "get" the string value of an Employee, e.g.

在不覆盖 ToString 的情况下，如果您尝试“获取”员工的字符串值，例如

var employee1= new Employee(); Console.WriteLine(employee1);

var employee1= new Employee(); Console.WriteLine(employee1);

What you'd get is:

你会得到的是：

ConsoleApplication1.Program+Employee

ConsoleApplication1.Program+Employee

Which provides no information at all to help you (or a UI) display relevant information.

它根本不提供任何信息来帮助您（或 UI）显示相关信息。

I use return _name + _number + _date + _salary;Which defaults to string,

我使用 return _name + _number + _date + _salary;默认为字符串，

or a more verbose

或更详细的

return "Name:" + _name + " Number:" + _number + " etc...";

return "Name:" + _name + " Number:" + _number + " etc...";

回答by MD Rakibuz Sultan

class Program
{
    static void Main( )
    {
        int Number = 10;
        Console.WriteLine(Number.ToString());

        Customer cc = new Customer();
        cc.FirstName = "Rakibuz";
        cc.LastName = "Sultan";

        Console.WriteLine(Convert.ToString(cc));

    }
}

public class Customer
{
    public string FirstName;
    public string LastName;

    public override string ToString()
    {
        return FirstName + " " + LastName;
    }

}