VB.NET/C# Comparison Operator for checking a set of elements - as an IN statement for SQL

Question

so in SQL you can do something like:

 WHERE title IN('title1','title2','title3')

to check for a set (assuming I'm using the correct phrase here). How can I do this in VB.NET/C#.NET?

Example:

 IF textMyTitle.text IN ("title1","title2","title 3") THEN
 'Take Action
 End If

Obviously, the IN part of this statement does not work ... What is the logical equivalent in .NET?

Answer 1

Try the following:

Dim titles As New List(Of String)()
titles.Add("title1")
titles.Add("title2")
titles.Add("title3")

If titles.Contains(textMyTitle.text) Then
    // Do something here
End If

Answer 2

There are several ways to do this. One of them is to create HashSetwith values ​​and check if it contains a string:

Dim values As new Hashet() { "title1", "title2", "title3" }
If values.Contains(textMyTitle.Text) Then
  ...
End If

, . HashSet O (1).

( 3.5 HashSet, Dictionary<string, byte>, .)

Answer 3

:

if((new string[] {"title1", "title2", "title3"}).Contains(textMyTitle.Text)
{
    ...
}

, , . - ( , IEnumerable<string>), :

List<string> titles = new List<string>();

// add titles to the list

...

if(titles.Contains(textMyTitle.Text))
{
    ...
}

Answer 4

IList - . .Net 2.0, Array IList < > . , IList:

string [] vars = new string [] { "title1", "title2", "title3" }; if (((IList) vars).Contains(textMyTitle.text)) {       // }

Answer 5

Depending on the type of kit you have. If you can choose the type of set you could just set in HastSet ()

so your example would look like (C #)

var set = new System.Collections.Generic.HashSet<string>(){"title1","title2","title 3"};
if set.Contains(textMyTitle.text)
   //Take Action

List and arrays have similar methods, although they won't work for large sets as well (they might be better for small sets, but I haven't tried)

Answer 6

I would use LINQ.

See this:

How to use LINQ Contains (string []) instead of Contains (string)