/*é*/
function check_form() {
    var f = $('f_excursion_request');
    var err = new Array();
    // check required
    var required = new Array('fname', 'surname','email', 'num_adults', 'num_children',
                             'card_number','name','security_code');
    for ( i = 0; i < required.length; i++ ) {
        var el = eval('f.'+required[i]);
        if ( el && el.value == '' ) {
            // please enter required fields
            err[err.length] = f.error_1.value;
            break;
        }
    }

    // check emails
    var reg_exp = /^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i;
    var email = f.email;
    if ( email && email.value != '' && !reg_exp.test(email.value) ) {
        // please enter valid email
        err[err.length] = f.error_2.value;
    }
    var reg_exp = /^\d+$/;
    // check card number and security code
    if ( ( f.card_number.value.length > 0 && !reg_exp.test(f.card_number.value) )
    ||   ( f.security_code.value.length > 0 && !reg_exp.test(f.security_code.value) ) ){
        // only digits
        err[err.length] = f.error_3.value;
    }
    // accept conditions
    if ( f.accept.checked == false ) {
        // you need to accept conditions
        alert(f.error_4.value);
        return;
    }

    // show errors
    if ( err.length > 0 ) {
        var msg = '';
        for ( var i = 0; i < err.length; i++ ) {
            msg += err[i]+"\n";
        }
        alert(msg);
    }
    else {
        f.submit();
    }
}