c# - How to check whether an element is in the stack

Determine whether an item is in the Stack
The Stack class represents a simple last-in-first-out non-generic collection of objects. The Stack capacity is the number of elements it can hold. When elements are added to a Stack, its capacity is automatically increased as required through reallocation. The Stack accepts null as a valid value and allows duplicate elements.

The following .net c# tutorial code demonstrates how we can check whether an item is in the Stack or not. In this .net c# tutorial code, we used the Stack class Contains() method to determine whether an element exists in the Stack instance.

The Stack class Contains(Object) method allows us to determine whether an element is in the Stack. The Stack class Contains(object? obj) method has a parameter named obj. The obj parameter is the object to locate in the Stack. The value can be null.

The Stack class Contains(Object) method returns a Boolean value. The method returns true if the obj is found in the Stack otherwise it returns false. This method determines equality by calling the Object.Equals method. The method performs a linear search
StackContainsMethod.aspx

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

<!DOCTYPE html>
<script runat="server">
    protected void Button1_Click(object sender, System.EventArgs e)
    {
        Stack colors = new Stack();

        colors.Push("BurlyWood");
        colors.Push("SaddleBrown");
        colors.Push("SandyBrown");
        colors.Push("Ivory");

        Label1.Text = "Stack Elements... ";
        Label1.Text += "<font color=SlateBlue>";
        foreach (string color in colors)
        {
            Label1.Text += "<br />" + color;
        }
        Label1.Text += "</font>";

        Label1.Text += "<br /><br />Is Element 'Ivory' Exists In Stack? " + colors.Contains("Ivory");
        Label1.Text += "<br />Is Element 'Salmon' Exists In Stack? " + colors.Contains("Salmon");
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>How to determine whether an element is in the Stack</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h2 style="color:MidnightBlue; font-style:italic;">
            System.Collections.Stack Contains() Method
            <br /> How to determine whether an element is in the Stack
        </h2>
        <hr width="475" align="left" color="Navy" />
        <br />
        <asp:Label
             ID="Label1"
             runat="server"
             ForeColor="SteelBlue"
             Font-Size="Large"
             Font-Names="Courier New"
             Font-Italic="true"
             Font-Bold="true"
             >
        </asp:Label>
        <br /><br />
        <asp:Button 
            ID="Button1"
            runat="server"
            OnClick="Button1_Click"
            Text="Test Stack Contains() Method"
            Height="45"
            Font-Bold="true"
            ForeColor="DodgerBlue"
            />
    </div>
    </form>
</body>
</html>
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