c# - How to filter an array elements

Array filter

The following asp.net c# example code demonstrate us how can we filter an array elements depends on specific criteria and get a new array object with filtered elements programmatically at run time in an asp.net application. .Net framework's Array Class Array.FindAll() method retrieve all the elements that match the conditions defined by the specified predicate.

Arry.FindAll<T>() method type parameter name is 'T' which represent the type of the elements of the array. FindAll() method has two required parameters named 'array' and 'match'. The 'array' parameter represent a one-dimensional array to search. And the 'match' parameter represent the Predicate<T> that defines the conditions of the elements to search for.

FindAll() method return an array object which contains all the elements that match the conditions. Finally, we can filter an array and get a new array object with filtered elements as this way NewArray = Array.FindAll(Condition).

array-filter.aspx


<%@ Page Language="C#" AutoEventWireup="true"%>  
  
<!DOCTYPE html>  
<script runat="server">  
    protected void Button1_Click(object sender, System.EventArgs e)  
    {
        string[] birds = new string[]
        {
            "Rock Parrot",
            "Crimson Rosella",
            "Regent Parrot",
            "Superb Parrot",
            "Red Lory",
            "African Emerald Cuckoo"
        };

        Label1.Text = "birds array.........<br />";
        foreach(string s in birds)
        {
            Label1.Text += s + "<br />";
        }

        //this line filter birds array and populate a new array.
        string[] filteredbirds = Array.FindAll(birds, x => x.EndsWith("Parrot"));

        Label1.Text += "<br />filtered birds array [ends with 'Parrot'].........<br />";
        foreach(string s in filteredbirds)
        {
            Label1.Text += s + "<br />";
        }
    }  
</script>  
  
<html xmlns="http://www.w3.org/1999/xhtml">  
<head id="Head1" runat="server">  
    <title>c# example - array filter</title>  
</head>  
<body>  
    <form id="form1" runat="server">  
    <div>  
        <h2 style="color:DarkBlue; font-style:italic;">  
            c# example - array filter
        </h2>  
        <hr width="550" align="left" color="LightBlue" />    
        <asp:Label   
            ID="Label1"   
            runat="server"  
            Font-Size="Large"  
            >  
        </asp:Label>  
        <br />
        <asp:Button   
            ID="Button1"   
            runat="server"   
            Text="array filter"  
            OnClick="Button1_Click"
            Height="40"  
            Font-Bold="true"  
            />  
    </div>  
    </form>  
</body>  
</html>

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