c# - How to truncate a string

Truncate a String
The String represents text as a sequence of UTF-16 code units. The String is a sequential collection of characters that is used to represent text. The String is a sequential collection of System.Char objects.

The following .net c# tutorial code demonstrates how we can truncate a String instance. So, in this .net c# tutorial code we will truncate a long String to a short length String. Here we will use String Substring() method to truncate a long-length String.

The String Substring() method retrieves a substring from this instance. The String Substring(Int32, Int32) method overload retrieves a substring from this instance where the substring starts at a specified character position and has a specified length.

The String Substring(int startIndex, int length) method overload has two required parameters. The startIndex parameter is the zero-based starting character position of a substring in this instance. And the length parameter is the number of characters in this substring. So, using this method we can truncate a String instance from any character position of the source String and also can truncate it in any length.

The String Substring(int startIndex, int length) method throws ArgumentOutOfRangeException if the startIndex plus length indicates a position that is not within this instance. Or startIndex or length is less than zero.

At last, we can add three dots to the truncated String. If we want to add the three dots at the end of a truncated String then we have to pass less than three for the length argument of the String Substring(int startIndex, int length) method.
string-truncate.aspx

<%@ Page Language="C#" AutoEventWireup="true"%>  
  
<!DOCTYPE html>    
<script runat="server">  
    protected void Button1_Click(object sender, System.EventArgs e)  
    {  
        //this section create a string variable.  
        string birds = "Snow Petrel. Royal Albatross. Laysan Albatross. Cape Petrel";  
  
        Label1.Text = "string of birds..................<br />";  
        Label1.Text += birds;

        string truncatedString = birds;
        string truncatedString2 = birds;

        if (birds.Length > 10)
        {
            //this line truncated string to 10 character.
            truncatedString = birds.Substring(0, 7);
            truncatedString += "...";

            //this line truncated string without using dotted.
            truncatedString2 = birds.Substring(0, 10);
        }

        Label1.Text += "<br /><br />truncated string 10 charcter limit.........<br />";
        Label1.Text += truncatedString;

        Label1.Text += "<br /><br />truncated string 10 charcter limit without dotted.........<br />";
        Label1.Text += truncatedString2;
    }    
</script>    
    
<html xmlns="http://www.w3.org/1999/xhtml">    
<head id="Head1" runat="server">    
    <title>c# example - string truncate</title>    
</head>    
<body>    
    <form id="form1" runat="server">    
    <div>    
        <h2 style="color:MidnightBlue; font-style:italic;">    
            c# example - string truncate
        </h2>    
        <hr width="550" align="left" color="Gainsboro" />    
        <asp:Label     
            ID="Label1"     
            runat="server"    
            Font-Size="Large"  
            >    
        </asp:Label>    
        <br /><br />  
        <asp:Button     
            ID="Button1"     
            runat="server"     
            Text="string truncate"    
            OnClick="Button1_Click"  
            Height="40"    
            Font-Bold="true"    
            />    
    </div>    
    </form>    
</body>    
</html>
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