用值初始化 C# 字典的正确方法？
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Proper way to initialize a C# dictionary with values?
提问by azrosen92
I am creating a dictionary in a C# file with the following code:
我正在使用以下代码在 C# 文件中创建字典：
private readonly Dictionary<string, XlFileFormat> FILE_TYPE_DICT
= new Dictionary<string, XlFileFormat>
{
{"csv", XlFileFormat.xlCSV},
{"html", XlFileFormat.xlHtml}
};
There is a red line under newwith the error:
new错误下方有一条红线：
Feature 'collection initilializer' cannot be used because it is not part of the ISO-2 C# language specification
无法使用功能“集合初始化程序”，因为它不是 ISO-2 C# 语言规范的一部分
Can anyone explain what is going on here?
谁能解释这里发生了什么？
EDIT:okay, so it turns out I was using .NET version 2.
编辑：好的，原来我使用的是 .NET 版本 2。
采纳答案by Haney
I can't reproduce this issue in a simple .NET 4.0 console application:
我无法在简单的 .NET 4.0 控制台应用程序中重现此问题：
static class Program
{
static void Main(string[] args)
{
var myDict = new Dictionary<string, string>
{
{ "key1", "value1" },
{ "key2", "value2" }
};
Console.ReadKey();
}
}
Can you try to reproduce it in a simple Console application and go from there? It seems likely that you're targeting .NET 2.0 (which doesn't support it) or client profile framework, rather than a version of .NET that supports initialization syntax.
您可以尝试在一个简单的控制台应用程序中重现它并从那里开始吗？您的目标似乎很可能是 .NET 2.0（不支持它）或客户端配置文件框架，而不是支持初始化语法的 .NET 版本。
回答by Zbigniew
Object initializers were introduced in C# 3.0, check which framework version you are targeting.
C# 3.0 中引入了对象初始值设定项，请检查您的目标框架版本。
回答by Vikram Kumar
With C# 6.0, you can create a dictionary in following way:
使用 C# 6.0，您可以通过以下方式创建字典：
var dict = new Dictionary<string, int>
{
["one"] = 1,
["two"] = 2,
["three"] = 3
};
It even works with custom types.
它甚至适用于自定义类型。
回答by Brendan
You can initialize a Dictionary(and other collections) inline. Each member is contained with braces:
您可以Dictionary内联初始化（和其他集合）。每个成员都包含在大括号中：
Dictionary<int, StudentName> students = new Dictionary<int, StudentName>
{
{ 111, new StudentName { FirstName = "Sachin", LastName = "Karnik", ID = 211 } },
{ 112, new StudentName { FirstName = "Dina", LastName = "Salimzianova", ID = 317 } },
{ 113, new StudentName { FirstName = "Andy", LastName = "Ruth", ID = 198 } }
};
See MSDNfor details.
有关详细信息，请参阅MSDN。
回答by Debendra Dash
Suppose we have a dictionary like this
假设我们有一个这样的字典
Dictionary<int,string> dict = new Dictionary<int, string>();
dict.Add(1, "Mohan");
dict.Add(2, "Kishor");
dict.Add(3, "Pankaj");
dict.Add(4, "Jeetu");
We can initialize it as follow.
我们可以按如下方式初始化它。
Dictionary<int, string> dict = new Dictionary<int, string>
{
{ 1, "Mohan" },
{ 2, "Kishor" },
{ 3, "Pankaj" },
{ 4, "Jeetu" }
};
回答by amesh
with c# 6.0
使用 C# 6.0
static class Program
{
static void Main(string[] args)
{
var myDict = new Dictionary<string, string>
{
["Key1"]="Value1",
["Key2"]="Value2"
};
Console.ReadKey();
}
}
