function isvalidstring(s) {
  var ok=0;var retval=false;
  for (i=0;i<s.length;i++) {     
    ichar=s.charCodeAt(i);
    if ( (ichar==32) || ((ichar>=65) && (ichar<=90)) ||  ((ichar>=97) && (ichar<=122)) || ((ichar>=48) && (ichar<=57)))
    ok++;
  }
  if (ok==s.length)
    retval=true;

  return retval;  
}

function isvalidnum(value) {
  var retval=1;
  if (isNaN(value)) {
    retval=0
  }
  return retval;
}

function isvalidemail (s) {
  var i = 1;
  var sLength = s.length;
  while ((i < sLength) && (s.charAt(i) != "@")) {
    i++
  }
  if ((i >= sLength) || (s.charAt(i) != "@")) return false;
  else i += 2;
  while ((i < sLength) && (s.charAt(i) != ".")) {
    i++
  }
  if ((i >= sLength - 1) || (s.charAt(i) != ".")) return false;
  else return true;
}

function isvalidurl(s) {
  var ok=0;
  var retval=false;

  for (i=0;i<s.length;i++) {
     ichar=s.charCodeAt(i);
     if ( (ichar==45) || (ichar==38) || (ichar==61) || (ichar==63) || (ichar==58) || (ichar==47) || (ichar==126) || (ichar==46) || (ichar==95) || (ichar==32) || ((ichar>=65) && (ichar<=90)) ||  ((ichar>=97) && (ichar<=122)) ||  ((ichar>=48) && (ichar<=57)) )
       ok++;
  }

  if (ok==s.length)
    retval=true;
 
  return retval;
}