function validate_form()
{
	valid = true;
	if (document.test.your_name.value =="")
	{
		alert ("Please enter your name.");
		valid=false;
	}
	 
	else if (document.test.your_email.value =="")
                   {
		alert("Please enter your email ID.")
		valid=false;
	}
	else if ((document.test.friend_email1.value =="")||(document.test.friend_email2.value =="")||(document.test.friend_email3.value =="")||(document.test.friend_email4.value =="")||(document.test.friend_email5.value ==""))
                   {
		alert("Please enter all 5 email addresses.")
		valid=false;
	}
	  
	else if (echeck(document.test.your_email.value)==false){
		 
		valid=false;
	}
	else if (echeck(document.test.friend_email1.value)==false){
		 valid=false;
	}
   	else if (echeck(document.test.friend_email2.value)==false){
		 valid=false;
	}
    else if (echeck(document.test.friend_email3.value)==false){
		 valid=false;
	}
	 else if (echeck(document.test.friend_email4.value)==false){
		 valid=false;
	}
	 else if (echeck(document.test.friend_email5.value)==false){
		 valid=false;
	}
	 
	
	
 
	 
 return valid;
}
  function isInteger (s)
   {
      var i;

      if (isEmpty(s))
      if (isInteger.arguments.length == 1) return 0;
      else return (isInteger.arguments[1] == true);

      for (i = 0; i < s.length; i++)
      {
         var c = s.charAt(i);

         if (!isDigit(c)) return false;
      }

      return true;
   }

   function isEmpty(s)
   {
      return ((s == null) || (s.length == 0))
   }

   function isDigit (c)
   {
      return ((c >= "0") && (c <= "9"))
   }
 
 
function echeck(str) {

		var at="@"
		var dot="."
		valid2 = true;
		var lat=str.indexOf(at)
		var lstr=str.length
		var ldot=str.indexOf(dot)
		if (str.indexOf(at)==-1){
		   alert("Some Email IDs seem invalid. Please check.")
		   valid2 = false;
		}

		else if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr){
		   alert("Some Email IDs seem invalid. Please check.")
		    valid2 = false;
		}

		else if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr){
		    alert("Some Email IDs seem invalid. Please check.")
		     valid2 = false;
		}

		else  if (str.indexOf(at,(lat+1))!=-1){
		    alert("Some Email IDs seem invalid. Please check.")
		     valid2 = false;
		 }

		 else if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot){
		    alert("Some Email IDs seem invalid. Please check.")
		     valid2 = false;
		 }

		else  if (str.indexOf(dot,(lat+2))==-1){
		    alert("Some Email IDs seem invalid. Please check.")
		     valid2 = false;
		 }
		
		else if (str.indexOf(" ")!=-1){
		    alert("Some Email IDs seem invalid. Please check.")
		     valid2 = false;
		 }

 		return valid2	;				
	}