String starts with number
the following c# example code demonstrate us how can we check whether a string starts with number. in this example code,
at first we convert the string to a char array using string ToCharArray() method. after creating a char array from string,
we take the first value of character array using ElementAt() method. at last we test the first char that it is a digit
or not using char IsDigit method.
TocharArray() method copy the characters of a string to a Unicode character array. ElementAt() method returns the element at a specified index in a sequence. Char IsDigit() method indicates whether a Unicode character is categorized as a decimal digit.
we also can directly determine the string starts with a number by Char.IsDigit(String, Int32) method. here string is the specified string and index value is (0) zero for string first character.
TocharArray() method copy the characters of a string to a Unicode character array. ElementAt() method returns the element at a specified index in a sequence. Char IsDigit() method indicates whether a Unicode character is categorized as a decimal digit.
we also can directly determine the string starts with a number by Char.IsDigit(String, Int32) method. here string is the specified string and index value is (0) zero for string first character.
string-starts-with-number.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 = "Winter Gilliflower. Bristly Groundberry";
string stringPlants2 = "1. Yellow Harlequin 2. Spotted Deadnettle 3. Meadow Holly";
Label1.Text = "string of plants..................<br />";
Label1.Text += stringPlants;
Label1.Text += "<br />"+stringPlants2;
//this line get string first/begin character
char stringFirstCharacter = stringPlants.ToCharArray().ElementAt(0);
//this line get string first/begin character
char stringFirstCharacter2 = stringPlants2.ToCharArray().ElementAt(0);
Boolean result = char.IsNumber(stringFirstCharacter);
Boolean result2 = char.IsNumber(stringFirstCharacter2);
//another option to test character number or letter
//Boolean result = char.IsDigit(stringFirstCharacter);
//Boolean result2 = char.IsDigit(stringFirstCharacter2);
Label1.Text += "<br /><br />stringPlants first character: " + stringFirstCharacter;
Label1.Text += "<br />stringPlants2 first character: " + stringFirstCharacter2;
Label1.Text += "<br /><br />stringPlants starts with number? " + result.ToString();
Label1.Text += "<br />stringPlants2 starts with number? " + result2.ToString();
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>c# example - string starts with number</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h2 style="color:MidnightBlue; font-style:italic;">
c# example - string starts with number
</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 number"
OnClick="Button1_Click"
Height="40"
Font-Bold="true"
/>
</div>
</form>
</body>
</html>

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