undefined index for PHP-Collection of common programming errors

hello people i am doing a function with calendar using AJAX and PHP

$showmonth = $_POST['showmonth'];
$showyear = $_POST['showyear'];
$pre_days = date ('w', mktime(0,0,0, $showmonth, 1, $showyear));
$post_days = (6 - (date('w', mktime(0, 0, 0, $showmonth, $day_count, $showyear))));

I keep getting error messages saying:

Notice: Undefined index: showmonth in C:\xampp\htdocs\calendar_start.php on line 2

Notice: Undefined index: showyear in C:\xampp\htdocs\calendar_start.php on line 3

Warning: cal_days_in_month() expects parameter 2 to be long, string given in C:\xampp\htdocs\calendar_start.php on line 8

Warning: mktime() expects parameter 4 to be long, string given in C:\xampp\htdocs\calendar_start.php on line 9

Warning: mktime() expects parameter 4 to be long, string given in C:\xampp\htdocs\calendar_start.php on line 10

I think it has something to do with my AJAX java script but i just dont know what there more parts to the AJAX code but i think this is the part troubling me

function next_month() {
    var nextmonth = showmonth + 1;
    if(nextmonth >12) {
        nextmonth = 1;
        showyear = showyear + 1;
        }
showmonth = nextmonth;
var hr = new XMLHttpRequest();
var url = "calendar_start.php";
var vars = "showmonth="+showmonth+"&showyear="+showyear;
hr.open("POST",url,true);
hr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
hr.onreadystatechange = function() {
    if(hr.readyState == 4 && hr.status == 200) {
        var return_data = hr.responseText;
        document.getElementById("showCalendar").innerHML = return_data;
        }
}
    hr.send(vars);
    document.getElementById("showCalendar").innerHTML = "processing...";
}

this maybe the problem too:

function initialCalendar() {
var hr = new XMLHttpRequest();
var url = "calendar_start.php";
var currentTime = new Date();
var month = currentTime.getMonth() + 1;
var year = currentTime.getFullYear();
showmonth = month;
showyear = year;
var vars = "showmonth="+showmonth+"&showyear="+showyear;
hr.open("POST", url, true);
hr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
hr.onreadystatechange = function() {
    if(hr.readyState == 4 && hr.status == 200) {
        var return_data = hr.responseText;
        document.getElementById("showCalendar").innerHML = return_data;
        }
}
    hr.send(vars);
    document.getElementById("showCalendar").innerHTML = "processing...";
}

1. Are you sending and receiving parameters using same method(POST/GET)…? if not so..it may give undefined index error… i.e. if your sending parameters using GET and receiving parameters using POST or vice versa..

2. If you change this in your javascript???

   var url = "calendar_start.php";
   var vars = "showmonth="+showmonth+"&showyear="+showyear;
   var final_url = url+"?"+vars;
   alert(final_url); //this line should a message with the url, post it please.
   hr.open("GET",final,true);
   

   That should works.

   PS: You pass your url with get params so in you php file you should receive them like

   $showmonth = $_GET['showmonth']; //I change POST by GET
   $showyear = $_GET['showyear']; //DONT forget to chenge this in your php file
   

   Saludos 😉

Originally posted 2013-11-09 23:20:05.