Duplicate values in multiple textbox - asp.net

Question

How to validate whether the text in multiple textboxes are unique from each other.
It looks like that in asp.net but its not a valid syntax
bool hasNoDuplicate = (txtEmergencyName1.Text.Trim() <> txtEmergencyName2.Text.Trim() <> txtEmergencyName3.Text.Trim <> txtEmergencyName4.Text.Trim);
I am looking for an efficient appraoch, kind of lambda expression or inbuilt in asp.net

Answer 1

Since you're asking for lambda, here's a linq approach.
var allTxt = new[] { txtEmergencyName1, txtEmergencyName2, txtEmergencyName3, txtEmergencyName4 };
var allText = allTxt.Select((txt, i) => new { Text = txt.Text.Trim(), Pos = i + 1 }).ToList();
bool hasNoDuplicate = !allText.Any(t => allText.Skip(t.Pos).Any(t2 => t.Text == t2.Text));
Put all relevant TextBoxes in a collection like an array and use Enumerable.Any. By skipping all before the current textbox you avoid checking the TextBoxes twice.
If all relevant TextBoxes are in a container control like a Panel, you could also use Enumerable.OfType to find them:
IEnumerable<TextBox> allTxt = this.EmergencyPanel.Controls.OfType<TextBox>();
Side-note: it's premature optimization anyway to look for the most performant way to validate some controls. This is nothing what you are doing constantly and there are never millions of controls. Instead you should look for the shortest or most readable approach.

Answer 2

You can use and && or or || operator accordingly
bool isDuplicate=(txtEmergencyName1.Text.Trim() == txtEmergencyName2.Text.Trim()
&& txtEmergencyName2.Text.Trim() == txtEmergencyName3.Text.Trim);
it will set true or false in the isDuplicate variable.
Edit 1
bool isDuplicate=(txtEmergencyName1.Text.Trim() == txtEmergencyName2.Text.Trim()
&& txtEmergencyName2.Text.Trim() == txtEmergencyName3.Text.Trim
&& txtEmergencyName1.Text.Trim() == txtEmergencyName3.Text.Trim
);

Answer 3

You could also do something like
var test = new TextBox();
var AlltBox = new List<TextBox>() { new TextBox() };
for(int i=1; i == 5;i++)
AlltBox.Add((TextBox)this.FindName("txtEmergencyName"+i));
bool exist = AlltBox.Any(tb => ((tb.Text == test.Text)&& tb.Name != test.Name));
but i don't know about the performance