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c# - How to check whether a string starts with vowel

Check whether a String starts with a vowel
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 check whether a String instance starts with a vowel. So, in this .net c# tutorial code we will determine whether a String object’s first character is a vowel or not. To check that we have to create a char array of all lowercase vowels. Then we will check whether the first character of the String instance is a vowel or not.

The String ToLower() method returns a copy of this String converted to lowercase. So using the ToLower() method we convert the String instance characters to lowercase.

Then we create a char array from the lowercase String instance. The String ToCharArray() method copies the characters in this instance to a Unicode character Array. So using this method we can create a char Array from a String instance.

Next, we will get the first element of the char array. The Enumerable ElementAt() method returns the element at a specified index in a sequence. So using this method we can get the first element of the char Array. The element is a Char object instance.

Finally, we will check whether the retrieved Char instance exists in the vowel char Array or not. If the char Array contains the specified Char instance then the String instance starts with a vowel.

The Enumerable Contains() method determines whether a sequence contains a specified element. So using this method we can determine whether the specified Char instance exists in the vowels Array or not.
string-starts-with-vowel.aspx

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

<!DOCTYPE html>  
<script runat="server"> 
    protected void Button1_Click(object sender, System.EventArgs e)  
    {
        //this section create string variables.
        string stringPlants = "Thimbleweed. Tassel Weed. Sweet Potato.";
        string stringPlants2 = "Orange Coneflower. Yellow Corydalis. White Tansy.";

        Label1.Text = "string of plants..................<br />";
        Label1.Text += stringPlants;
        Label1.Text += "<br />"+stringPlants2;

        //this line create a char array.
        char[] vowels = { 'a', 'e', 'i', 'o', 'u' };

        //this line get string first/begin character (lower case)
        char firstCharacter = stringPlants.ToLower().ToCharArray().ElementAt(0);

        //this line get string first/begin character (lower case)
        char firstCharacter2 = stringPlants2.ToLower().ToCharArray().ElementAt(0);

        //test string starts with vowel or not
        Boolean result = vowels.Contains(firstCharacter);
        Boolean result2 = vowels.Contains(firstCharacter2);

        Label1.Text += "<br /><br />stringPlants first character: " + firstCharacter;
        Label1.Text += "<br />stringPlants2 first character: " + firstCharacter2;

        Label1.Text += "<br /><br />stringPlants starts with vowel? " + result.ToString();
        Label1.Text += "<br />stringPlants2 starts with vowel? " + result2.ToString();
    }  
</script>  

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