Validate user input

[dukeb]

I want to validate user input. As an example, on an ma crossover, the user enters a 5 for the long trend and a 20 for the short trend. The entries have been reversed.
What method do I use to notify the user at input time that there has been an error?

[NinjaTrader_Joydeep]

Hello dukeb,
You can do the validation in the setter of the property. A sample code will be like

[Description("Period for slow MA")]

[GridCategory("Parameters")]
public int Slow
{
	get { return slow; }
	set 
	{
		slow = Math.Max(1, value);
		
		if (fast > slow)   //fast is the other property
		{
			System.Windows.Forms.MessageBox.Show("Fast cannot be greater than Slow");
			//do some other stuffs	
		}
	}
}

Please let me know if I can assist you any further.

[dukeb]

Thank you ...
Under the '//do some other stuffs' category..
If I do return; will this allow the user to change the input.

In otherwords, I do not want the program to proceed unless this condition has been met.

[NinjaTrader_Joydeep]

Hello dukeb,
You can validate the values first and then set the value if everything is right. Its normal C# procedures.