function isBlank(s){
	var len=s.length
	var i
	 for(i=0;i<len;++i){
	   if(s.charAt(i) !="" || s.charAt(i)!=" ") 
	   return false
	    }
		return true
		
		}

function containC(fieldName,fieldValue,C_value){
	 var argvalue = fieldValue.toString()
	var len=argvalue.length
	var i
	 for(i=0;i<len;++i){
	   if(argvalue.charAt(i) == C_value) 
	   return true
	    }
	    alert(fieldName +" Must contain the '"+C_value+"'.")
		return false
		}  

function validate(fieldName,fieldValue){
	 var argvalue = fieldValue.toString()

		if(isBlank(argvalue)){
		 alert(fieldName+" cannot be left blank.")
		  return false
		  }
		  return true
		  }
 

function validateName(){
		   return validate("The name field ", document.feedback.txtName.value)
		   }

function validateEmail(){
		   if(validate("The e-mail field ",document.feedback.txtEmail.value))
		       if(containC("The e-mail field ", document.feedback.txtEmail.value,"@"))
			     return containC("The e-mail field ", document.feedback.txtEmail.value,".")
			 else
			   return false
		  }


function  isNum(fieldName, fieldValue){
   var argvalue = fieldValue.toString()

  if (argvalue.length == 0)
    return false;

  for (var n = 0; n < argvalue.length; n++)
    if (argvalue.substring(n, n+1) < "0" || argvalue.substring(n, n+1) > "9"){
	  alert(fieldName+" are not all digits!")
      return false;
   }
	return true
 }

function validateComments(){
		   return validate("The Message field ",document.feedback.txtComments.value)		  
          }
			
function validatePhone(){
	if( validate(" The contact No.field ", document.feedback.txtTel.value))
	   return isNum(" The contact No. field ", document.feedback.txtTel.value)
	   else
	     return false
		 }
			
function validateFeedback(){
			if(!validateName())
			    return false
				if(!validateEmail())
				  return false
				  if(!validatePhone())
				    return false
				  if(!validateComments())
				   return false
				   else 
				   return true
		 }