如何在 C# 中的控制台窗口中显示列表项
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How to display list items on console window in C#
提问by
I have a Listwhich contains all databases names. I have to dispaly the items contained in that list in the Console (using Console.WriteLine()). How can I achieve this?
我有一个List包含所有数据库名称的。我必须在控制台中显示该列表中包含的项目（使用Console.WriteLine()）。我怎样才能做到这一点？
回答by Jon Skeet
Assuming the items override ToStringappropriately:
假设项目ToString适当地覆盖：
public void WriteToConsole(IEnumerable items)
{
foreach (object o in items)
{
Console.WriteLine(o);
}
}
(There'd be no advantage in using generics in this loop - we'd end up calling Console.WriteLine(object)anyway, so it would still box just as it does in the foreachpart in this case.)
（在这个循环中使用泛型没有任何好处——Console.WriteLine(object)无论如何我们最终都会调用，所以它仍然会像foreach在这种情况下的部分那样装箱。）
EDIT: The answers using List<T>.ForEachare very good.
编辑：使用的答案List<T>.ForEach非常好。
My loop above is more flexible in the case where you have an arbitrary sequence (e.g. as the result of a LINQ expression), but if you definitely have a List<T>I'd say that List<T>.ForEachis a better option.
在您有任意序列的情况下（例如作为 LINQ 表达式的结果），我上面的循环更灵活，但如果您肯定有一个，List<T>我会说这List<T>.ForEach是一个更好的选择。
One advantage of List<T>.ForEachis that if you have a concrete list type, it will use the most appropriate overload. For example:
的一个优点List<T>.ForEach是，如果您有一个具体的列表类型，它将使用最合适的重载。例如：
List<int> integers = new List<int> { 1, 2, 3 };
List<string> strings = new List<string> { "a", "b", "c" };
integers.ForEach(Console.WriteLine);
strings.ForEach(Console.WriteLine);
When writing out the integers, this will use Console.WriteLine(int), whereas when writing out the strings it will use Console.WriteLine(string). If no specific overload is available (or if you're just using a generic List<T>and the compiler doesn't know what Tis) it will use Console.WriteLine(object).
写出整数时，这将使用Console.WriteLine(int)，而写出字符串时，它将使用Console.WriteLine(string)。如果没有特定的重载可用（或者如果您只是使用泛型List<T>而编译器不知道是什么T），它将使用Console.WriteLine(object).
Note the use of Console.WriteLineas a method group, by the way. This is more concise than using a lambda expression, and actually slightlymore efficient (as the delegate will justbe a call to Console.WriteLine, rather than a call to a method which in turn just calls Console.WriteLine).
Console.WriteLine顺便说一下，请注意作为方法组的使用。这比使用lambda表达式更加简洁，并且实际上稍微更有效（作为代表将刚刚是一个呼叫Console.WriteLine，而不是这又只是调用方法的调用Console.WriteLine）。
回答by CasperT
You can also use List's inbuilt foreach, such as:
您还可以使用 List 的内置 foreach，例如：
List<T>.ForEach(item => Console.Write(item));
This code also runs significantlyfaster!
这段代码的运行速度也明显更快！
The above code also makes you able to manipulate Console.WriteLine, such as doing:
上面的代码也让你能够操作 Console.WriteLine，比如：
List<T>.ForEach(item => Console.Write(item + ",")); //Put a,b etc.
回答by Svish
Actually you can do it pretty simple, since the list have a ForEachmethod and since you can pass in Console.WriteLineas a method group. The compiler will then use an implicit conversion to convert the method group to, in this case, an Action<int>and pick the most specific method from the group, in this case Console.WriteLine(int):
实际上你可以做的很简单，因为列表有一个ForEach方法，因为你可以Console.WriteLine作为一个方法组传入。然后，编译器将使用隐式转换将方法组转换为 anAction<int>并从组中选择最具体的方法，在本例中为Console.WriteLine(int)：
var list = new List<int>(Enumerable.Range(0, 50));
list.ForEach(Console.WriteLine);
Works with strings too =)
也适用于字符串 =)
To be utterly pedantic (and I'm not suggesting a change to your answer - just commenting for the sake of interest) Console.WriteLineis a method group. The compiler then uses an implicit conversion from the method group to Action<int>, picking the most specific method (Console.WriteLine(int)in this case).
完全迂腐（我不建议改变你的答案——只是为了兴趣而评论）Console.WriteLine是一个方法组。然后编译器使用从方法组到 的隐式转换Action<int>，选择最具体的方法（Console.WriteLine(int)在本例中）。
回答by BlackCoffee
Console.WriteLine(string.Join<TYPE>("\n", someObjectList));
回答by Bhramar
While the answers with List<T>.ForEachare very good.
虽然答案List<T>.ForEach很好。
I found String.Join<T>(string separator, IEnumerable<T> values)method more useful.
我发现String.Join<T>(string separator, IEnumerable<T> values)方法更有用。
Example :
例子 ：
List<string> numbersStrLst = new List<string>
{ "One", "Two", "Three","Four","Five"};
Console.WriteLine(String.Join(", ", numbersStrLst));//Output:"One, Two, Three, Four, Five"
int[] numbersIntAry = new int[] {1, 2, 3, 4, 5};
Console.WriteLine(String.Join("; ", numbersIntAry));//Output:"1; 2; 3; 4; 5"
Remarks :
评论 ：
If separator is null, an empty string (String.Empty) is used instead. If any member of values is null, an empty string is used instead.
如果分隔符为null，则使用空字符串 ( String.Empty) 代替。如果 values 的任何成员为null，则使用空字符串代替。
Join(String,?IEnumerable<String>)is a convenience method that lets you concatenate each element in an IEnumerable(Of String)collection without first converting the elements to a string array. It is particularly useful with Language-Integrated Query (LINQ) query expressions.
Join(String,?IEnumerable<String>)是一种方便的方法，可让您连接IEnumerable(Of String)集合中的每个元素，而无需先将元素转换为字符串数组。它对于语言集成查询 (LINQ) 查询表达式特别有用。
This should work just fine for the problem, whereas for others, having array values. Use other overloads of this same method, String.Join Method (String,?Object[])
这应该可以很好地解决问题，而对于其他人来说，具有数组值。使用相同方法的其他重载String.Join Method (String,?Object[])
Reference: https://msdn.microsoft.com/en-us/library/dd783876(v=vs.110).aspx
参考：https: //msdn.microsoft.com/en-us/library/dd783876(v=vs.110).aspx
回答by Adola
I found this easier to understand:
我发现这更容易理解：
List<string> names = new List<string> { "One", "Two", "Three", "Four", "Five" };
for (int i = 0; i < names.Count; i++)
{
Console.WriteLine(names[i]);
}
回答by Chamila Maddumage
Assume that we need to view some data in command prompt which are coming from a database table. First we create a list. Team_Details is my property class.
假设我们需要在命令提示符中查看一些来自数据库表的数据。首先我们创建一个列表。Team_Details 是我的属性类。
List<Team_Details> teamDetails = new List<Team_Details>();
Then you can connect to the database and do the data retrieving part and save it to the list as follows.
然后就可以连接数据库，进行数据检索部分，保存到列表中，如下所示。
string connetionString = "Data Source=.;Initial Catalog=your DB name;Integrated Security=True;MultipleActiveResultSets=True";
using (SqlConnection conn = new SqlConnection(connetionString)){
string getTeamDetailsQuery = "select * from Team";
conn.Open();
using (SqlCommand cmd = new SqlCommand(getTeamDetailsQuery, conn))
{
SqlDataReader rdr = cmd.ExecuteReader();
{
teamDetails.Add(new Team_Details
{
Team_Name = rdr.GetString(rdr.GetOrdinal("Team_Name")),
Team_Lead = rdr.GetString(rdr.GetOrdinal("Team_Lead")),
});
}
Then you can print this list in command prompt as follows.
然后你可以在命令提示符下打印这个列表，如下所示。
foreach (Team_Details i in teamDetails)
{
Console.WriteLine(i.Team_Name);
Console.WriteLine(i.Team_Lead);
}
