📄 demo-if.aspx
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<%@ Page Language="C#" Debug="true" %>
<script runat="server">
void page_Load()
{
if(Page.IsPostBack)
{
// Clean up from prior tests
lblFax.Text = "";
lblTel.Text="";
txtTel.Visible=false;
// end Clean up from prior tests
// if syntax option #1
// Only have actions if expression is true
// and only one line of action
if (chkFaxConfirm.Checked == true) lblFax.Text = "We will confirm by fax.";
// if syntax option #2
// Only have actions if expression is true
// multiple lines of action
if (chkTelConfirm.Checked == true)
{
lblTel.Text = "We will confirm by telephone. Please enter your number";
txtTel.Visible =true;
}
// if syntax option #3
if (chkShipByGovernment.Checked == true)
{
lblAddress.Text = "Please enter your post office box number";
txtAddress.Visible=true;
}
else
{
lblAddress.Text = "Please enter your street address";
txtAddress.Visible=true;
}
// if syntax option #3 alternate - Tenary form
// one comand each for true and false conditions
lblCustomsFormRequired.Text=(chkCustomsFormRequired.Checked == true ? "We will provide a customs form" : "We will not fill in a customs form");
// if syntax option #4
if(chkIsMember.Checked==true)
{
lblOut.Text = "Members get free handling";
lblOut.BackColor=System.Drawing.Color.LightPink;
}
else if(Convert.ToInt32(txtAge.Text)<=18)
{
lblOut.Text = "Handling fee for students = ¥300";
lblOut.BackColor=System.Drawing.Color.LightCyan;
}
else
{
lblOut.Text = "Price is ¥500";
lblOut.BackColor=System.Drawing.Color.LightSeaGreen;
} //end else of if stack of syntax option #4
} //end if(Page.IsPostBack)
} //end page_Load()
</script>
<html>
<head>
</head>
<body>
<form runat="server">
<asp:Button id="Button1" runat="server" Text="Submit for all syntaxes"></asp:Button>
<hr />
<h3>if syntax option #1
</h3>
Fax Confirm?
<asp:CheckBox id="chkFaxConfirm" runat="server" Checked="false"></asp:CheckBox>
<asp:Label id="lblFax" runat="server"></asp:Label>
<br />
<hr />
<h3>if syntax option #2
</h3>
Telephone Confirm?
<asp:CheckBox id="chkTelConfirm" runat="server" Checked="false"></asp:CheckBox>
<asp:Label id="lblTel" runat="server"></asp:Label>
<asp:TextBox id="txtTel" runat="server" Visible="false"></asp:TextBox>
<hr />
<h3>if syntax option #3
</h3>
Ship by Government Post?
<asp:CheckBox id="chkShipByGovernment" runat="server" Checked="false"></asp:CheckBox>
<asp:Label id="lblAddress" runat="server"></asp:Label>
<asp:TextBox id="txtAddress" runat="server" Visible="false"></asp:TextBox>
<br />
<hr />
<h3>if syntax option #3 - alternate form - Ternary
</h3>
International customs form required?
<asp:CheckBox id="chkCustomsFormRequired" runat="server" Checked="false"></asp:CheckBox>
<asp:Label id="lblCustomsFormRequired" runat="server"></asp:Label>
<br />
<hr />
<h3>if syntax option #4
</h3>
Please answer questions below to calculate your handling charge<br />
Members = free Students = ¥300 Others = ¥500 <br />
Your age = <asp:TextBox id="txtAge" runat="server" width=40></asp:TextBox>
Are you a member (check means yes)? <asp:CheckBox id="chkIsMember" runat="server"></asp:CheckBox><br>
Your handling charge is:
<asp:Label id="lblOut" runat="server"><br /></asp:Label>
</form>
</body>
</html>
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