Console.WriteLine 中的 {0} 代表什么?

本文介绍了Console.WriteLine 中的 {0} 代表什么?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

给定代码:

// person.cs using System; // #if false class Person { private string myName = "N/A"; private int myAge = 0; // Declare a Name property of type string: public string Name { get { return myName; } set { myName = value; } } // Declare an Age property of type int: public int Age { get { return myAge; } set { myAge = value; } } public override string ToString() { return "Name = " + Name + ", Age = " + Age; } public static void Main() { Console.WriteLine("Simple Properties"); // Create a new Person object: Person person = new Person(); // Print out the name and the age associated with the person: Console.WriteLine("Person details - {0}", person); // Set some values on the person object: person.Name = "Joe"; person.Age = 99; Console.WriteLine("Person details - {0}", person); // Increment the Age property: person.Age += 1; Console.WriteLine("Person details - {0}", person); } } // #endif

代码的输出是:

Simple Properties Person details - Name = N/A, Age = 0 Person details - Name = Joe, Age = 99 Person details - Name = Joe, Age = 100

Console.WriteLine("Person details - {0}", person); 中的 {0} 代表什么?怎么换成 Name..... 了?

What does the {0} in Console.WriteLine("Person details - {0}", person); stands for ? How come it's replaced by Name..... ?

当我使用 {1} 而不是 {0} 时，我得到一个异常...

When I put {1} instead of {0} I get an exception ...

推荐答案

如您所见，您的 person 对象上有一个返回字符串的代码，控制台检查您的对象上是否存在名称为 ToString 的字符串类型类与否，如果存在则返回你的字符串:

As you can see, There's a code on your person object that returns a string, Console checks for If a type of string with name of ToString exists on your object class or not, If exists then It returns your string:

public override string ToString() { return "Name = " + Name + ", Age = " + Age; }

并且 {0} 是格式化的消息，当您将其定义为 {0} 时，这意味着打印/格式化您插入到函数的 params 参数中的零索引对象.这是一个从零开始的数字，用于获取您想要的对象的索引，这是一个示例:

And {0} Is a formatted message, When you define It to {0} It means printing/formatting the zero Index object that you Inserted Into params arguments of your function. It's a zero based number that gets the index of object you want, Here's an example:

Console.WriteLine("{0} Is great, {1} Do you think of It? {2} Think {0} Is great!", "C#", "What", "I"); // C# Is great, What do you think of It? I think C# Is great!

当您说 {0} 时，它会获取 C# 或您的对象 [] 的 [0].

When you say {0} It gets C# or the [0] of your object[].