string array.Contains?

Question

.NET 2

string[] myStrings = GetMyStrings();    
string test = "testValue";

How can I verify if myStrings contains or not test?

Answer 1

bool ContainsString(string[] arr, string testval)
{
    if ( arr == null )
        return false;
    for ( int i = arr.Length-1; i >= 0; i-- )
        if ( arr[i] == testval )
            return true;
    return false;
}

And this will have the best performance ever. :P

Answer 2

Instead of using a static array, you could use a List:

List<string> myStrings = new List<string>(GetMyStrings());
if(myStrings.Contains("testValue"))
{
    // Do Work
}

Answer 3

I assume you want to check if any elements in your array contains a certain value (test). If so you want to construct a simple loop. In fact I think you should click here.

Answer 4

Here's a .NET 2.0 compliant approach. Using Array.Find will return null if the value isn't found.

C# Approach

string[] myStrings = { "A", "B", "testValue" };
string test = "testValue";
string result = Array.Find(myStrings, delegate(string s) { return s == test; });
Console.WriteLine("Result: " + result);

If you need a case insensitive match use s.Equals(test, StringComparison.InvariantCultureIgnoreCase).

EDIT: with VB.NET 2.0 more effort is required since it doesn't support anonymous delegates. Instead you would need to add a Function and use AddressOf to point to it. You would need to set the testValue as a member or property since it will not be passed in to the predicate method. In the following example I use Array.Exists.

VB.NET Approach

' field or property ' 
Dim test As String = "testValue"

Sub Main
    Dim myStrings As String() = { "A", "B", "testValue" }       
    Dim result As Boolean = Array.Exists(myStrings, AddressOf ContainsValue)
    Console.WriteLine(result)
End Sub

' Predicate method '
Private Function ContainsValue(s As String) As Boolean
    Return s = test
End Function

Answer 5

In .NET 2.0, you could do the following if you want the index:

int index = Array.FindIndex(
    myStrings,
    delegate(string s) { return s.Equals(test); }
);

index will be -1 if myStrings does not contain test.

If you merely want to check for existence:

bool exists = Array.Exists(
    myStrings,
    delegate(string s) { return s.Equals(test); }
);

Answer 6

Here is almost the exact same question on msdn. Find String in String Array As others have said you really have two options: 1) Use a list for easier checking 2) Loop through your array to find the string

Answer 7

How about this:

Sub Main
    Dim myStrings(4) As String
    myStrings(0) = "String 1"
    myStrings(1) = "String 2"
    myStrings(2) = "testValue"
    myStrings(3) = "String 3"
    myStrings(4) = "String 4"

    Dim test As String = "testValue"

    Dim isFound As Boolean = Array.IndexOf(myStrings, test) >= 0

    If isFound Then
        Console.WriteLine("Found it!")
    End If
End Sub

This should work for .Net 2.0 and VB.Net.

Answer 8

you can use Array.BinarySearch as described below.

 string[] strArray = GetStringArray();
        string strToSearch ="test";
        Array.BinarySearch(strArray, strToSearch);