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Null Reference Exception particularly means that the object you are currently using, does not exist in the memory. You can easily get rid of this error in many ways,
var obj = new ObjectType();
if(obj == null) {
} else {
}
var value = obj?.Property;
Yet, there are many other ways to hide this. But in my own opinion, if you encounter null reference exception, then you should not try to avoid it, but have a look at why was it there in the first place. The object, in your Charting.Axis etc, they are null, I would say, Axis was null as you are trying to call a function on it. So, do check them. And properly create an instance of them so that this error can go away.
Also read this, What Is A Null Error in Code Execution
The sh*t I complain about
It's like there ain't a cloud in the sky and it's raining out - Eminem
~! Firewall !~
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Bonjour tout le monde. Je m'appelle Arridano, étudiant en commerce, 2e année. Est-ce possible pour quelqu'un de moyen en math d'apprendre à coder facilement ? Merci d'avance pour vos différentes réponses.
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The primary language of the forum is English. You can use any translate service to post your question here in English.
modified 20-Sep-20 21:01pm.
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-----------------------------------------login.jsp--------------------------------------
<pre lang="HTML">
<%@page import="java.util.*" %>
<%@page import="java.io.*" %>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<form action="login.jlc" method="post">
<%
String st1="";
String st2="";
Cookie cks[]=request.getCookies();
if(cks!=null){
for(Cookie c1:cks){
if(c1.getName().equals("unm")){
st1=c1.getValue();
}
if(c1.getValue().equals("pwd")){
st2=c1.getValue();
}
}
}else{
System.out.println("NO COOKIES FOUND");
}
%>
<table>
<tr>
<td colspan="2" align="center">ACCOUNT LOGIN</td>
</tr>
<tr>
<td>
<h2>USERNAME</h2>
</td>
<td><input type="text" name="username" value="<%=st1%>"/></td>
</tr>
<tr>
<td>
<h2>PASSWORD</h2>
</td>
<td>
<input type="password" name="password" value="<%=st2%>"/>
</td>
</tr>
<tr>
<td>
<input type="checkbox" name="rem" />REMEMBERME<br>
</td>
</tr>
<tr>
<td>
<input type="submit" value="login"/>
</td>
</tr>
</table>
</form>
</body>
</html>
</pre>
---------------------------------------loginServlet-----------------------------------------
<pre lang="java">
package com.jlc;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class LoginServlet extends HttpServlet {
protected void service(HttpServletRequest req,HttpServletResponse res)throws ServletException,IOException{
PrintWriter out=res.getWriter();
String unm=req.getParameter("username");
String pwd=req.getParameter("password");
String rem=req.getParameter("rem");
if(unm.equals(pwd)){
if(rem!=null){
Cookie ck1=new Cookie("u",unm);
Cookie ck2=new Cookie("p",pwd);
res.addCookie(ck1);
res.addCookie(ck2);
Cookie c[]=req.getCookies();
for(Cookie c1:c){
c1.setMaxAge(-1);
}
}
}else{
out.println("INCORRECT USERNAME PASSWORD");
}
}//service
}//class
</pre>
-- modified 8-Apr-17 3:38am.
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1) An unformatted code-dump is not a question.
2) Storing the username and password in cookies is an EXTREMELY bad idea. Please tell us which site(s) your code will be deployed on, so that we can blacklist them.
3) Look at the cookie names you're setting, then look at the cookie names you're trying to read.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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I know that this question probably have been asked many times before but things changes over time.
We are developing a huge website in size comparison to facebook. It will be very unique design wise and should be pixel perfect from the design. As we see it most of the features in the bootstrap framework will only take resources, as much of those will not be used or highly customized using less in our case.
Is bootstrap still really the right way to go for this project or should we just base it on normalize?
We know the development will be heavily decreased with bootstrap but that doesn't matter.
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Member 13110077 wrote: should be pixel perfect from the design
Start by giving up on that unrealistic goal.
Trying to make the site a "pixel perfect" match for a design image is hard enough in a single browser at a fixed resolution. Once you start throwing in multiple browsers at different resolutions, it becomes virtually impossible. So unless you're going to add a 90's style footer saying "This site is best viewed in Internet Explorer 4 at 1024x768", it's not going to work.
Member 13110077 wrote: much of those will not be used or highly customized
So either customise Bootstrap[^], and remove the components you're not going to use; or don't use Bootstrap.
If you're not going to use most of the features from Bootstrap, then it wouldn't make sense to use Bootstrap. There are other lightweight frameworks available that you could base your site on - eg: W3.CSS Home[^]. Or you could build your CSS from scratch, which would give you complete control.
There's no point fighting to adapt a framework that isn't a good fit for your requirements.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Thanks for your answer. Do you have any examples of some frameworks that just takes care of these basic problems as normalize does that should be used even though i am writing my own css?
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Normalize will give you a good baseline to start from, with no extraneous fluff.
If you want to start with a framework, W3.CSS[^] seems to be relatively light-weight (4.78Kb), and seems to include quite a few utility classes.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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I need MVC PHP Complete Course and guideline, if anybody can help me i shall be thankful to you.
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Your favorite web search engine can help.
Just feed it with "MVC PHP course" and "MVC PHP tutorial".
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This is my first google result, PHP Master | The MVC Pattern and PHP, Part 1[^]
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
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please tell me how data transfer from database into dropDownList automatically.
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You need to write code to bind it. Lots of examples online.
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
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It will not happen automatically until you code for it.
modified 20-Sep-20 21:01pm.
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I want to learn how to create my own themes in Wordpress, and I've also read about (and separately been recommended) using the Bootstrap framework to do so.
Now, I do have I would say beginner/intermediate level HTML experience, I've obviously used Dreamweaver and, years ago, Frontpage, to design websites. I can modify Wordpress themes to make appearance difference, I know my way around a CSS stylesheet, but I'm certainly not at the level of being able to create a theme from scratch. My HTML knowledge is pretty archaic also.
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Member 13099347 wrote: I want to learn how to create my own themes in Wordpress I would suggest googling for that very thing. "How to create theme in Wordpress."
My first result looks very promising: Building a WordPress Theme in 60 Seconds[^]
60 seconds is not bad.
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
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Hi everyone, thanks for always being there for me. I need your help again on this. i created a forum from scratch which has friends system with it.. i am short of ideas on how i can do a one-to-one chat for the users who might want to contact their friends. Please i need help on how i can go about it. thank you
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Google for examples.
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
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Hello everyone,
Could someone please have a look at this PHP Code and help me solve the problem please. I'm trying to send an email from this form but its not working. Any help please it would be great-full.
<?php
$emailSubject = 'Crazy PHP Scripting';
$webMaster = 'e_chauffeur@hotmail.com';
$fullnameField = $_POST['fullname'];
$emailField = $_POST['email'];
$telephoneField = $_POST['telephone'];
$purposeJourneyField = $_POST['purposejourney'];
$vehicletypeField = $_POST['vehicletype'];
$journeyFromField = $_POST['journeyfrom'];
$startDestinationPostcodeField = $_POST['startdestinationpostcode'];
$dateField = $_POST['date'];
$hourField = $_POST['hour'];
$minuteField = $_POST['minute'];
$ampmField = $_POST['ampm'];
$journeyToField = $_POST['journeyto'];
$endDestinationPostcodeField = $_POST['enddestinationpostcode'];
$returnField = $_POST['return'];
$returnField = $_POST['return'];
$returnJourneyDateField=$_POST['returnjourneydate'];
$returnhourField = $_POST['returnhour'];
$returnminuteField = $_POST['returnminute'];
$returnampmField = $_POST['returnampm'];
$messageField = $_POST['message'];
$body = <<<EOD
<br><hr><br>
Name: $fullnameField <br>
Email: $emailField <br>
Phone Number: $telephoneField <br>
Purpose Of Jurney: $purposejourneyField <br>
Vehicle Type: $vehicletypeField <br>
Journey From: $journeyfromField <br>
Start Dest Postcode: $startdestinationpostcodeField <br>
Date Start: $dateField <br>
Start Time Pickup: $hourField ":" $minuteField $ampmField <br>
Journey To: $journeytoField <br>
End Dest Postcode: $enddestinationpostcodeField <br>
Return Journey: $returnField <br>
Date Return Journey: $returnjourneydateField <br>
Return Time Pickup: $returnhourField ":" $returnminuteField $returnampmField <br>
Message: $messageField <br>
EOD;
$headers = "From: $emailField\r\n";
$headers .= "Content-type: text/html\r\n";
$success = mail($webMaster, $emailSubject, $body, $headers);
$theResults = <<<EOD
<html>
<head>
<title>Success Message</title>
<style type="text/css">
<!--
body {
width: Auto;
height: 100%;
font-size:16px;
font-family:Arial Rounded MT Bold;
padding-top: 10px;
padding-bottom: 10px;
padding-left: 10px;
padding-right: 10px;
}
-->
</style>
</head>
<body>
<div>
<div> Thank you for contacting us. We will contact you ver shortly...</div>
</div>
</body>
</html>
EOD;
echo "$theResults";
?>
Thanks in advance everyone
kind regards
Roni
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"Not working" is not very informative.
Try to find out where the problems are located (creating the mail or sending it).
Note that using PHP: mail - Manual[^] requires proper setup in php.ini and sendmail.ini.
Some SMTP servers have specific requirements which must be met. You are using HotMail. So a research about "php mail hotmail" might help.
Finally you might also think about replacing the build-in mail support by an additional module like GitHub - PHPMailer/PHPMailer: The classic email sending library for PHP[^]. These provide you with detailed error messages (SMTP error codes) while the build-in function only returns a boolean value.
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I posted this in the Lounge yesterday. I'm feeling pretty good about getting my app working.
Then Sander asked this question, so I thought I'd start this thread to get more info.
Thanks for pointing out my folly Sander.
Here is the JavaScript code that I have now. It listens to a SignalR service, which notifies it when a record is changed. Right now I have an ajax call that refreshes the whole grid. Ya, bad idea.. but I just wanted to get it working.
<script src="/Scripts/jquery-3.1.1.min.js"></script>
<script src="/Scripts/jquery.signalR-2.1.2.js"></script>
<script src="~/signalr/hubs"></script>
<script type="text/javascript">
$(function () {
<pre>
var conn = $.hubConnection("http://blah:8094/signalr");
var proxy = conn.createHubProxy('dashboardHub')
proxy.on('notifyAllClientsOfChanges', function () {
var searchUrl = "Index/GetData";
$.ajax({
url: searchUrl,
type: "POST",
success: function (data) {
$("#divData").html(data);
}
});
});
conn.start().done(function ()
{
console.log("Connected!!!");
}).fail(function (e)
{
console.log('Unable to connect:' + e);
});
});
So, what I'd really like is to pass the updated record through the notifyAllClientsOfChanges method into the code above and have it add the record to the WebGrid, or update it of it already exists.
I'm very new to this, so can anyone point me in the right direction? Any examples of doing this?
Thanks
If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.
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You'll need to change your back-end as well.
I've once created some example with some stock and put it on GitHub (GitHub - SanderRossel/starting-signalr: Examples on how to use SignalR.[^]).
You can checkout the StockHub.cs[^] file and the Index.js[^] files.
The important parts are these:
StockHub.cs
Clients.All.updateAmount(id, newAmount); Index.js
stockHub.client.updateAmount = function (id, amount) {
var product = stock().filter(function (p) { return p.id === id })[0];
if (product) {
product.amount(amount);
}
}; As you can see I'm passing some data from C# to JavaScript so I can just process it in JavaScript.
I'm not sure how that works out for your example, but you could put whatever data Index/GetData returns into your SignalR function to pass to your front-end.
Hope that helps, good luck
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I'm back on this project now. In your JS code above you have:
var product = stock().filter(function (p) { return p.id === id })[0];
I'm guessing it trying to find the data row, but I don't understand the syntax. Can you please explain it to me?
If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.
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From the top of my head, stock() returns an array, which has a filter() function.
The filter() function takes a predicate as parameter, which is simply a function that returns true or false for each element p in the array.
In this case the predicate (function (p) { ... }) returns true when element p.id === id (where the id variable declaration is not visible in this code sample).
The filter function returns a new array containing all elements for which the predicate returned true.
From that array I'm selecting the 0th element (since an id is unique we expect 0 or 1 elements to be returned).
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