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c# - How to get a range of elements from an array

Get a range of elements from an Array
The Array class provides methods for creating, manipulating, searching, and sorting arrays. The Array class is not part of the System.Collections namespaces. However, it is still considered a collection because it is based on the IList interface. An element is a value in an Array. The length of an Array is the total number of elements it can contain. The Array has a fixed capacity.

The following .net c# tutorial code demonstrates how we can get a range of elements from an Array instance. That means we will get a specified number of elements from an Array instance and create a new instance of an Array object by the returned elements.

Here we will copy the specified elements from an Array object and create a new instance of an Array instance by copied elements. In this .net c# tutorial code we used the Array Copy() method to copy some elements from the source Array and create a new instance of an Array.

The Array Copy() method copies a range of elements in one Array to another Array and performs type casting and boxing as required. The Array Copy(Array, Int32, Array, Int32, Int32) method overload copies a range of elements from an Array starting at the specified source index and pastes them to another Array starting at the specified destination index. The length and the indexes are specified as 32-bit integers. So using this method overload .net developers can get a range of elements from an Array instance and create another Array instance from copied elements.

The Array Copy (Array sourceArray, int sourceIndex, Array destinationArray, int destinationIndex, int length) method’s sourceArray parameter is the Array that contains the data to copy. The sourceIndex parameter is a 32-bit integer that represents the index in the sourceArray at which copying begins. The destinationArray parameter is the Array that receives the data. The destinationIndex parameter is a 32-bit integer that represents the index in the destinationArray at which storing begins. And the length parameter is a 32-bit integer that represents the number of elements to copy.

The Array Copy (Array sourceArray, int sourceIndex, Array destinationArray, int destinationIndex, int length) method throws several exceptions such as it throws ArgumentNullException if the sourceArray is null or the destinationArray is null. The method throws RankException if the sourceArray and destinationArray have different ranks. It throws ArrayTypeMismatchException if the sourceArray and destinationArray are of incompatible types.
array-get-range.aspx

<%@ Page Language="C#" AutoEventWireup="true"%>  

<!DOCTYPE html>  
<script runat="server">  
    protected void Button1_Click(object sender, System.EventArgs e)  
    {
        string[] birds = new string[]
        {
            "Wood Thrush",
            "Japanese Thrush",
            "Mistle Thrush",
            "Austral Thrush",
            "Green Cochoa"
        };

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

        //new destination (copied) array length
        int length = 3;
        //copy start from index 1. second element from birds array.
        int index = 1;

        string[] copiedRange = new string[length];
        Array.Copy(birds, index, copiedRange, 0, length);

        Label1.Text += "<br />new array from birds array [index range 1 to 3].........<br />";
        foreach (string s in copiedRange)
        {
            Label1.Text += s + "<br />";
        }
    }  
</script>  

<html xmlns="http://www.w3.org/1999/xhtml">  
<head id="Head1" runat="server">  
    <title>c# example - array get range</title>  
</head>  
<body>  
    <form id="form1" runat="server">  
    <div>  
        <h2 style="color:DarkBlue; font-style:italic;">  
            c# example - array get range
        </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 get range"  
            OnClick="Button1_Click"
            Height="40"  
            Font-Bold="true"  
            />  
    </div>  
    </form>  
</body>  
</html>
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