assign cookie value to a var..

Question

fuston05 0 Junior Poster in Training

15 Years Ago

I set my cookie on a previouse page, this page here i call it and set it to a var, then when i echo it it says undefined var. Just curious.. im missing something simple here.. not sure what it is. Cookie is set, i verified that. and if i echo the cookie directly it works fine, its just when i echo the var that i assigned cookie value to that is undefined. any advise is greatly appreciated. thanks

<html>
<head></head>
<body>
<?php
if(isset($_COOKIE["num_tape"]) ){
   $num_tape= $_COOKIE["num_tape"];
   $supplies= TRUE;
}

Echo $num_tape;
?>
</body>
</html>

php

3 Contributors
6 Replies
125 Views
14 Hours Discussion Span
Latest Post 15 Years Ago Latest Post by fuston05

Dani AI

Generated 9 Months Ago

A few practical takeaways from this thread and the follow-ups by , and :

When a cookie value prints fine but a local variable shows "undefined", the cause is usually not the cookie itself but the script flow or a tiny syntax/placement issue that prevents the assignment from running. Useful checks are to make sure the assignment runs before the echo, that the code path containing the assignment actually executes (form-conditionals, redirects, early returns), and that included files or stray output aren't interfering with program flow.

Effective diagnostics (built on suggestions already posted) are: enable full error reporting, inspect the request superglobals to confirm the cookie exists, and log or dump execution points to see which blocks run. The PHP manual pages for cookies and for debugging functions are good references: Cookies in PHP and var_dump. Also check for headers/output issues (see headers_sent) and for invisible characters (BOM) in included files that can change behavior.

A few robustness tips to avoid similar surprises going forward: initialize variables explicitly (or use the null-coalescing pattern in newer PHP), keep cookie-reading logic near the top of the request flow so it isn’t hidden inside a conditional that may not execute, always validate/sanitize values from cookies (filter_var and strict casting), and keep comments on their own lines after the PHP open tag to avoid odd parser/editor interactions. Logging small checkpoints (simple dumps or error_log calls) makes root-cause hunting much faster than guessing.

Short checklist: confirm $_COOKIE contents, confirm the assignment block executed, enable errors and dumps, inspect included files for stray output/BOM, and initialize/sanitize the resulting variable before use.

All 6 Replies

jkon 738 Posting Whiz in Training

15 Years Ago

Do a simple test in order to understand what is happening in this point of flow (some editors have php debuggers , not easy to set but really useful)

<html>
<head></head>
<body>
<?php
if( isset($_COOKIE["num_tape"]))
{
   $num_tape	= $_COOKIE["num_tape"];
   $supplies	= TRUE;
   var_dump($num_tape);
}
else 
{
	echo "undefined<br/>";
	var_dump($_COOKIE);
}
?>
</body>
</html>

blocblue 238 Posting Pro in Training

15 Years Ago

Hi,

$num_tape is out of scope. Try something like:

$numTape = isset($_COOKIE['num_tape']) ? $_COOKIE['num_tape'] : null;
echo $numTape;

Plus, always remember to sanitise variables from cookies, as they're easy to tamper with.

R.

Edited 15 Years Ago by blocblue because: n/a

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fuston05 0 Junior Poster in Training · Answer 1 · 2011-02-01T07:37:08+00:00

Hi,
$num_tape is out of scope. Try something like:
$numTape = isset($_COOKIE['num_tape']) ? $_COOKIE['num_tape'] : null;
echo $numTape;
Plus, always remember to sanitise variables from cookies, as they're easy to tamper with.
R.

Ill try your suggestion, Im sorry for being a total noob but im unfaliliar with the syntax you laid out.. what is the "?" in the middle of that statement?

fuston05 0 Junior Poster in Training · Answer 2 · 2011-02-01T07:41:21+00:00

I used the code for testing and it all looked good. Its something to do with where i am setting the var.
heres my entire page:

<?php require("includes/header.php"); ?>
<?php//vars from form_1
	if(isset($_POST["submit"]) ){
		
		if(isset($_COOKIE["num_tape"]) ){
			$num_tape= $_COOKIE["num_tape"]; 
			$supplies= TRUE;
		}
		if(isset($_COOKIE["num_brushes"]) ){$num_brushes= $_COOKIE["num_brushes"]; $supplies= TRUE;}
		if(isset($_COOKIE["num_naps"]) ){$num_naps= $_COOKIE["num_naps"]; $supplies= TRUE; }
		if(isset($_COOKIE["num_plastic"]) ){$num_plastic= $_COOKIE["num_plastic"]; $supplies= TRUE;}
		if(isset($_COOKIE["puddy"]) ){$puddy= $_COOKIE["puddy"]; $supplies= TRUE;}
		if(isset($_COOKIE["rags"]) ){$rags= $_COOKIE["rags"]; $supplies= TRUE;}
		if(isset($_COOKIE["gas"]) ){$gas= $_COOKIE["gas"]; $supplies= TRUE;}
		
		//vars from form_2
		if(isset($_POST["prep"]) ){$prep= $_POST["prep"]; }
		if(isset($_POST["trim_primer"]) ){$trim_primer= $_POST["trim_primer"]; }
		if(isset($_POST["lin_ft"])  ){$lin_ft= $_POST["lin_ft"];
			}else{
			$errors= "Must fill in Linear Ft in order to continue";
			header("Location: build_form_2.php?e=$errors")  ;}

		if(isset($_POST["wall_len"]) ){$wall_len= $_POST["wall_len"]; }
		if(isset($_POST["wall_width"]) ){$wall_width= $_POST["wall_width"]; }
		if(isset($_POST["ceil_height"]) ){$ceil_height= $_POST["ceil_height"]; }
		if(isset($_POST["walls_primer"]) ){$walls_primer= $_POST["walls_primer"]; }
		if(isset($_POST["cathedral"]) ){$cathedral= $_POST["cathedral"]; }
		if(isset($_POST["tex_ceil"]) ){$tex_ceil= $_POST["tex_ceil"]; }
		if(isset($_POST["num_windows"]) ){$num_windows= $_POST["num_windows"]; }
		if(isset($_POST["num_doors"]) ){$num_doors= $_POST["num_doors"]; }
	
}
?>			
<h1>Step 3: Just a few more details.</h1>
<br />
<div id= "build_form_3">
				
	<form action= "" method= "post">
	<?php																																						
	
	echo $num_tape;
	
				
		if(isset($_POST["submit"]) ){																				 
			echo "<input type= \"submit\" name= \"submit\" 
			value= \"Submit\" /><br />";
		}
	?>	
	</form>
	<br />
																																																																																																																																						
</div> 
<?php require("includes/footer.php");?>

I noticed that if i assign the cookie to the var down where i am trying to echo it it works just fine. Its just the place where i am assigning the $var.. weird.. i dont get it. I use the $var in this same scope all the time for post and get vars, works fine, but not this time..

fuston05 0 Junior Poster in Training · Answer 3 · 2011-02-01T08:00:48+00:00

Hi,
$num_tape is out of scope. Try something like:
$numTape = isset($_COOKIE['num_tape']) ? $_COOKIE['num_tape'] : null;
echo $numTape;
Plus, always remember to sanitise variables from cookies, as they're easy to tamper with.
R.

that didnt work either. i appreciate your efforts so far though

fuston05 0 Junior Poster in Training · Answer 4 · 2011-02-01T08:04:45+00:00

I got it.. it was the stupid comment at the top.. i moved it down 1 line and now all works fine.. thanks for all your help guys.. i knew it had to be something really small.. lol thanks much everyone :)

assign cookie value to a var..

Dani AI

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