c# - How to trim a string to a specified length

Trim a String to a specified length
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 trim a String object to a specified length. So, we will truncate a long String to a specified length. We can also add three dots at the end of the truncated string while we trim a long-length String instance.

The String Substring() method retrieves a substring from this instance. The String Substring(int startIndex, int length) method retrieves a substring from this instance. The substring starts at a specified character position and has a specified length. So we can pass zero for the start index and a specified number for the length to truncate/trim a String instance.

The String Substring(Int32, Int32) method returns a String that is equivalent to the substring of length that begins at the start index in this instance or empty. This method throws ArgumentOutOfRangeException if startIndex plus length indicates a position that is not within this instance.

We can add three dots at the end of the truncated/trimmed String. To do that we have to get a substring less than three from the specified length to trim. After that, we will add three dots at the end of the truncated String. Finally, using the Substring() method we can trim/truncate a long String to a specified length.
string-trim-to-length.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 = "Southern Giant Petrel. Sooty Shearwater. Macaroni Penguin";  
  
        Label1.Text = "string of birds..................<br />";  
        Label1.Text += birds;

        string trimmed20Char = birds;
        string trimmedWithoutDot = birds;

        if (birds.Length > 10)
        {
            //this line truncated/trimmed string to 20 character.
            trimmed20Char = birds.Substring(0, 17);
            trimmed20Char += "...";

            //this line truncated string without using dotted.
            trimmedWithoutDot = birds.Substring(0, 20);
        }

        Label1.Text += "<br /><br />trimmed string 20 charcter length limit.........<br />";
        Label1.Text += trimmed20Char;

        Label1.Text += "<br /><br />trimmed string 20 charcter length limit without dotted.........<br />";
        Label1.Text += trimmedWithoutDot;
    }    
</script>    
    
<html xmlns="http://www.w3.org/1999/xhtml">    
<head id="Head1" runat="server">    
    <title>c# example - string trim to length</title>    
</head>    
<body>    
    <form id="form1" runat="server">    
    <div>    
        <h2 style="color:MidnightBlue; font-style:italic;">    
            c# example - string trim to length
        </h2>    
        <hr width="550" align="left" color="Gainsboro" />    
        <asp:Label     
            ID="Label1"     
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            Font-Size="Large"  
            >    
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        <br /><br />  
        <asp:Button     
            ID="Button1"     
            runat="server"     
            Text="string trim to length"    
            OnClick="Button1_Click"  
            Height="40"    
            Font-Bold="true"    
            />    
    </div>    
    </form>    
</body>    
</html>
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