c# - String startswith case insensitive

String startswith case insensitive

The following asp.net c# example code demonstrate us how can we determine whether a string starts with a specified substring (string comparison is ignoring case) programmatically at run time in an asp.net application.

.Net framework's String Class String.StartsWith(String, StringComparison) overloaded method can determine whether the beginning of this string instance matches the specified string when compared using the specified comparison option.

String.StartsWith(String, StringComparison) method has two required parameters named 'value' and 'comparisonType'. The 'value' parameter represent the string to compare. The 'comparisonType' parameter value type is 'System.StringComparison' which represent one of the enumeration values that determines how this string and specified string (value parameter) are compared.

System.StringComparison enumeration value 'OrdinalIgnoreCase' allow us to compare strings using ordinal sort rules and ignoring the case (case insensitive) of the strings being compared.

This method return a Boolean value. It return 'true', if this instance begins with 'value' parameter value; otherwise it return 'false'.

So, we can check whether a string begins with specified substring by ignoring case in this way String.StartsWith(String, StringComparison.OrdinalIgnoreCase)

string-startswith-case-insensitive.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 stringPlants = "Coffee Plant. Eastern Coneflower. Pale Corydalis";

        Label1.Text = "string of plants..................<br />";
        Label1.Text += stringPlants;

        string wordToCheck = "Coffee";
        string wordToCheck2 = "Coneflower";
        string wordToCheck3 = "CoFFee";

        //this line check string starts with/begin with 'Coffee' or not / ignore case
        Boolean result = stringPlants.StartsWith(wordToCheck, StringComparison.OrdinalIgnoreCase);

        //this line check string starts with/ begin with 'Coneflower' or not / ignore case
        Boolean result2 = stringPlants.StartsWith(wordToCheck2, StringComparison.OrdinalIgnoreCase);

        //this line check string starts with/begin with 'CoFFee' or not / ignore case
        Boolean result3 = stringPlants.StartsWith(wordToCheck3, StringComparison.OrdinalIgnoreCase);

        Label1.Text += "<br /><br /> string starts with [Coffee] ignore case? " + result.ToString();
        Label1.Text += "<br />string starts with [Coneflower]? ignore case" + result2.ToString();
        Label1.Text += "<br />string starts with [CoFFee] ignore case? " + result3.ToString();
    }  
</script>  
  
<html xmlns="http://www.w3.org/1999/xhtml">  
<head id="Head1" runat="server">  
    <title>c# example - string startswith case insensitive</title>  
</head>  
<body>  
    <form id="form1" runat="server">  
    <div>  
        <h2 style="color:MidnightBlue; font-style:italic;">  
            c# example - string startswith case insensitive
        </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 startswith case insensitive"  
            OnClick="Button1_Click"
            Height="40"  
            Font-Bold="true"  
            />  
    </div>  
    </form>  
</body>  
</html>

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