c# - How to check whether a string contains numbers only

String contains numbers only
string-contains-numbers-only.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 stringValue = "this is a sample 5 string 7 with number";
        string stringNumbers = "123456789502";

        Label1.Text = "string..................<br />";
        Label1.Text += "stringValue: " + stringValue;
        Label1.Text += "<br />stringNumbers: " + stringNumbers;

        //this line check string contains only digit/numeric value/number or not.
        Boolean isNumeric = stringValue.All(char.IsDigit);

        //this line check string contains only digit/numeric value/number or not.
        Boolean isNumeric2 = stringNumbers.All(char.IsDigit);

        Label1.Text += "<br /><br />stringValue contains only number (digit, numeric value)?.........";
        Label1.Text += isNumeric.ToString();

        Label1.Text += "<br /><br />stringNumbers contains only number (digit, numeric value)?...........";
        Label1.Text += isNumeric2.ToString();
    }  
</script>  
  
<html xmlns="http://www.w3.org/1999/xhtml">  
<head id="Head1" runat="server">  
    <title>c# example - string contains numbers only</title>  
</head>  
<body>  
    <form id="form1" runat="server">  
    <div>  
        <h2 style="color:MidnightBlue; font-style:italic;">  
            c# example - string contains numbers only
        </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 contains numbers only"  
            OnClick="Button1_Click"
            Height="40"  
            Font-Bold="true"  
            />  
    </div>  
    </form>  
</body>  
</html>
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