$_POST return an array - php

Question

I have a recent issue with a $_POST.
When I write :
print_r($_POST['nb_acces']);
I get :
1
Which is the value I wrote in the form.
But if I write :
$nb_acces = $_POST['nb_acces'];
print_r($nb_acces )
I get :
Array ( [nb] => 0 )
It was working before, and now I don't understand what happens. Could it be from a server configuration or something ?
EDIT :
My input :
<form id='sous_paiement' name='sous_paiement' method='post' action='commande_enregistre_test.php?ecole=<?php echo $id_ecole; ?>'>
<input id='nb_acces' name='nb_acces' style='width:90px;border:1px solid black;padding-left:4px;text-align:center;' />
Yes if I use $_POST['nb_acces'] I can echo the value. Though I wish to check the value to have an integer and avoid injection.
The way I get this array is the point I don't understand. I have only one input.
Could it come from my checking JavaScript function (sorry for french words, I remove here any non digit characters and calculate some prices) :
function filtre_saisie() {
var input_acces = document.getElementById("nb_acces");
var nb_acces = input_acces.value.replace(/[^0-9]/g, '');
input_acces.value = nb_acces;
var prix_unitaire = calcul_prix_unitaire(nb_acces);
var prix_total = calcul_prix_total(nb_acces);
document.getElementById("div_prix_unitaire").innerHTML = prix_unitaire;
document.getElementById("div_prix_total").innerHTML = prix_total;
}
Could it be this replace ?
EDIT 2 ----------------------------------
Well the whole form :
<form id='sous_paiement' name='sous_paiement' method='post' action='commande_enregistre_test.php?ecole=<?php echo $id_ecole; ?>'>
<div class="div_categories">
<p style='margin:0;padding:3px;padding-left:60px;'>Indiquez le <strong>nombre d'accès</strong> que vous souhaitez acheter :</p>
</div>
<br />
<div id="erreur_nb_acces" style="color:red;"><br /></div>
<table style='border-collapse:collapse;'>
<tr style='font-weight:bold;border:1px solid #eee;background-color:white;'>
<td style='width:200px;padding-left:10px;'>Nombre d'accès</td>
<td style='width:100px;padding-left:10px;padding-right:10px;'><input id='nb_acces' name='nb_acces' type="text" style='width:90px;border:1px solid black;padding-left:4px;text-align:center;' /></td>
</tr>
</table>
<br />
<table style='border-collapse:collapse;'>
<tr style='border:1px solid #eee;background-color:white;border-bottom:1px solid #999;'>
<td style='width:200px;padding-left:10px;'>Prix par accès</td>
<td style='width:100px;padding-left:10px;padding-right:10px;text-align:right;'><div id='div_prix_unitaire' style='display:inline;'>-</div> €</td>
</tr>
<tr style='font-weight:bold;border:1px solid #999;background-color:white;'>
<td style='width:200px;padding-left:10px;'>PRIX TOTAL</td>
<td style='width:100px;padding-left:10px;padding-right:10px;text-align:right;'><div id='div_prix_total' style='display:inline;'>-</div> €</td>
</tr>
</table>
<div style='width:190px;margin-top:5px;'>
Consulter les tarifs</span>
</div>
<div style="clear:both;"></div>
<br /><br />
<div class="div_categories">
<p style='margin:0;padding:3px;padding-left:60px;'>Choisissez votre <strong>mode de paiement</strong> :</p>
</div>
<br /><br />
<table class="tab_mode_paiement" style="border-collapse:collapse;">
<tr>
<td>
<input id='paiement_cb' name='mode_paiement' value='5' class='eleves' type='radio' checked="checked" style="cursor:pointer" />
</td>
<td style="font-weight:bold;padding-right:80px;border-right:1px solid #999;">
<label for='paiement_cb' style="cursor:pointer">
<img src="../images/ic_cb.jpg" style="float:left;display:inline;padding-right:10px;" /> Carte bancaire
</label>
</td>
<td style="padding-left:40px;">
<!--<input id='paiement_paypal' name='mode_paiement' value='3' class='eleves' type='radio' style="cursor:pointer" />-->
</td>
<td style="font-family:arial;font-size:20px;padding-right:120px;">
<!--<label for='paiement_paypal' style="cursor:pointer">
<span style="color:rgba(0,3,128,1)">Pay</span><span style="color:rgba(0,158,210,1)">Pal</span>
</label>-->
</td>
<td>
<input id='paiement_virement' name='mode_paiement' value='1' class='eleves' type='radio' style="cursor:pointer" />
</td>
<td style="font-weight:bold;">
<label for='paiement_virement' style="cursor:pointer">
Par virement bancaire
</label>
</td>
</tr>
<tr>
<td colspan="2" style="border-right:1px solid #999;">Recevez vos accès immédiatement</td>
<td colspan="4" style="padding-left:90px;">Accès disponibles après réception du paiement</td>
</tr>
</table>
<br /><br /><br />
<input id='enregistrer' name='enregistrer' value='Enregistrer la commande' type='button' onclick='verif_sous_paiement();' style='width:300px;height:40px;' />
<br /><br />
<br />
</form>
And my Javascript :
<script>
function ouvrirPopUp_tarifs() {
window.open ('tarifs.php', 'tarifs', config='height=370, width=760, toolbar=no, menubar=no, scrollbars=yes, resizable=no, location=no, directories=no, status=no');
}
var tab_responsables = new Array();
var tab_acces_responsables = new Array();
var nb_responsables = 0;
function initialiser_filtre_saisie() {
setInterval("filtre_saisie()", 200);
}
function filtre_saisie() {
var input_acces = document.getElementById("nb_acces");
var nb_acces = input_acces.value.replace(/[^0-9]/g, '');
input_acces.value = nb_acces;
var prix_unitaire = calcul_prix_unitaire(nb_acces);
var prix_total = calcul_prix_total(nb_acces);
document.getElementById("div_prix_unitaire").innerHTML = prix_unitaire;
document.getElementById("div_prix_total").innerHTML = prix_total;
}
function verif_sous_paiement() {
filtre_saisie();
var nb_acces = document.getElementById("nb_acces").value;
if (nb_acces == 0) {
document.getElementById("erreur_nb_acces").innerHTML = "Veuillez indiquer un <strong>nombre d'accès</strong>.";
document.getElementById('nb_acces').focus();
}
else {
document.getElementById('sous_paiement').submit();
}
}
</script>
Seems my whole code afraid everybody -.-

Answer 1

You are missing the type="text" attribute in your input, even the browser asumes that's a text, this might cause you some problems;
<input type="text" id='nb_acces' name='nb_acces' .......... />
Also, seems like you're replace anything that starts with a number, like 1 with a empty value, that's why you get a 0:
var nb_acces = input_acces.value.replace(/\d/g, '')

Answer 2

Well, I saw the message of someone who told me to check with var_dump, and it helped me to figure now why there is this issue. I don't know why this message has been erased as it helped me a lot. Thanks to who posted it.
If someone has the same issue, but I know it comes from an old and probably bad server configuration, to use $nb_acces and $_POST['nb_acces'] generates a conflict. Don't use the same name. That's all -.-