function imgShow(pSrc) {
  var z = pSrc.src;
  var len = z.length;
  var tmp = '';
  
  len -= 5;
  z.charAt(len) == '0' ? tmp = '1' : tmp = '0';
  pSrc.src = z.substr(0, len) + tmp + z.substr(len + 1, z.length - 1);
}

function checkCourseForm(pStr) {
  var form = document.forms[pStr];
  var msg = '';

  if (form.fCompany.value == '') msg += '- brak nazwy firmy\n';
  if (form.fName.value == '') msg += '- brak imienia\n';
  if (form.fSurname.value == '') msg += '- brak nazwiska\n';
  if (form.fPhone.value == '') msg += '- brak numeru telefonu\n';
  if (form.fEmail.value == '') msg += '- brak adresu email\n';
  if (form.fComment.value == '') msg += '- brak uwag lub zapytania\n';

  if (msg != '') {
    alert('Błąd:\n' + msg);
    return false;
  } else return true;

}

function checkOrderForm(pStr) {
  var form = document.forms[pStr];
  var msg = '';

  if (form.fCompany.value == '') msg += '- brak nazwy firmy\n';
  if (form.fName.value == '') msg += '- brak imienia\n';
  if (form.fSurname.value == '') msg += '- brak nazwiska\n';
  if (form.fPhone.value == '') msg += '- brak numeru telefonu\n';
  if (form.fEmail.value == '') msg += '- brak adresu email\n';
  
  if (form.fStreet.value == '') msg += '- brak ulicy\n';
  if (form.fNum.value == '') msg += '- brak numeru\n';
  if (form.fPostal.value == '') msg += '- brak kodu pocztowego\n';
  if (form.fCity.value == '') msg += '- brak miejscowości\n';

  if (msg != '') {
    alert('Błąd:\n' + msg);
    return false;
  } else return true;

}