c# - How to i get my textbox to only allow numbers 1-14? -

this have far, getting error.

try {     dblnights = convert.todouble(txtnights.text);      if (dblnights > 1 && 14)     {     }     else     {         string script = "alert(\"number of nights must between 1 , 14!\");";         scriptmanager.registerstartupscript(this, gettype(), "servercontrolscript", script, true);         txtnights.focus();     } }//end try  catch {     string script = "alert(\"number of nights must integer!\");";     scriptmanager.registerstartupscript(this, gettype(), "servercontrolscript", script, true);      txtnights.focus(); }//end catch 

i not quite sure make show error box if numbers besides 1-14 entered. else working, not that. doing wrong?

thank you.

problem : not using logical and operator.

this:

       if (dblnights > 1 && 14)         {          } 

must be:

       if (dblnights >= 1 && dblnights <= 14)         {              /*valid range thing here*/         } 

edit: suggested eric lippert in comments show usage of tryparse.

if use double.tryparse() can eliminate exceptions may occur invalid data.because double.tryparse() method return boolean value true if conversion successful otherwise returns false avoid try catch blocks.

try this:

        double dblnights;         if (double.tryparse(txtnights.text, out dblnights))         {             //conversion successfull         }         else         {             //conversion failed         }