PHP script beginner

apss_evaluator · 05-02-2016, 04:40 AM

Hi PHP guru's

I've started playing on a php scripting following cbt video of Dean Davis. I'm using now XAMPP as my testing area of the codes. For some reason there is a section on the video where I'm testing the UNSET variable and brings me this error:

Code:

Notice: Undefined index: version in C:\xampp\htdocs\qq.php on line 18

strangely from the video provided it should not throw an error.

This is the code I'm using:

PHP Code:



<? 
 
$arr1 = array("browser" => "mozilla", "agent" => "firefox"); 
echo $arr1["browser"], "\t", $arr1["agent"]; 
 
$arr1["version"] = "0.9.1"; 
echo $arr1["version"]; 
 
$arr1["browser"] = "netscape"; 
echo "<p>", $arr1["browser"]; 
 
unset($arr1["version"]); 
echo $arr1["version"]; 
 
?> 
 
</body> 
</html>

Turbocapitalist · 05-02-2016, 05:06 AM

Which distro are you using? It would be easier for you and easier for people to help you if you work with the normal LAMP stack which is provided in your distro's repository. The directions vary depending on which distro you have but they are all quick and low-effort to install.

XAMPP is for Windows and those that try to shoehorn it onto GNU/Linux find that it costs a lot of extra work and headache.

That said, if I recall PHP, the blocks of code should start with '<?php' instead of '<?' alone.

apss_evaluator · 05-02-2016, 05:21 AM

Quote:

Originally Posted by Turbocapitalist

Which distro are you using? It would be easier for you and easier for people to help you if you work with the normal LAMP stack which is provided in your distro's repository. The directions vary depending on which distro you have but they are all quick and low-effort to install.

XAMPP is for Windows and those that try to shoehorn it onto GNU/Linux find that it costs a lot of extra work and headache.

That said, if I recall PHP, the blocks of code should start with '<?php' instead of '<?' alone.

I'm using windows 7 with xampp lite v3.2.2

with regards on the <?php instead of '<?' I already managed to enable short tags on and worked out

hydrurga · 05-02-2016, 05:43 AM

You've unset the variable (destroyed it) and then asked PHP to print the variable out. It can't do this because you've just unset it, it doesn't exist any more.

P.S. http://php.net/manual/en/function.array-key-exists.php

apss_evaluator · 05-02-2016, 05:50 AM

Quote:

Originally Posted by hydrurga

You've unset the variable (destroyed it) and then asked PHP to print the variable out. It can't do this because you've just unset it, it doesn't exist any more.

P.S. http://php.net/manual/en/function.array-key-exists.php

Is there a way that I can eliminate this:

Code:

Notice: Undefined index: version in C:\xampp\htdocs\qq.php on line 18

I'm following the tutorial video and would like to sync the outputs the same

hydrurga · 05-02-2016, 06:06 AM

I have no idea what the video is telling you to do, apss_evaluator. All I know is that you've unset an array element and then you're trying to print that array index, hence the error. PHP can't find the index "version" in the $arr1 array because it doesn't exist any more.

You can test for the existence of an array index using the function I referred to.

keefaz · 05-02-2016, 06:33 AM

You could disable notice report

PHP Code:



error_reporting(E_ALL & ~E_NOTICE);
unset($arr1["version"]);
echo $arr1["version"];

But as hydrurga said, the version key doesn't exist anymore so what the point trying to echo this non existent item

apss_evaluator · 05-02-2016, 08:46 AM

Quote:

Originally Posted by keefaz

You could disable notice report

PHP Code:



error_reporting(E_ALL & ~E_NOTICE); 
unset($arr1["version"]); 
echo $arr1["version"];

But as hydrurga said, the version key doesn't exist anymore so what the point trying to echo this non existent item

The video tells when it echo the unsetted key pair it will show nothing beside the "netscape"

simply the results should be like this:

Code:

mozilla	firefox0.9.1
netscape

instead of this I'm getting:

Code:

mozilla	firefox0.9.1
netscape
Notice: Undefined index: version in C:\xampp\htdocs\qq.php on line 18

urbanwks · 05-02-2016, 09:29 AM

Quote:

Originally Posted by apss_evaluator

instead of this I'm getting:

Code:

mozilla	firefox0.9.1
netscape
Notice: Undefined index: version in C:\xampp\htdocs\qq.php on line 18

This is the expected output. I tested in PHP 5.5.6 and got the same result. I see what he's trying to prove - that if you unset the variable, then there's nothing to display. That's essentially what you successfully proved by receiving that notice.

Either the instructor has notice reporting turned off somewhere (as keefaz suggested), or perhaps he's using an older version of PHP that doesn't throw the notice. I can't tell you when or if there was a version where this notice wouldn't show up, but I don't remember there ever being a case where what you're trying to do didn't throw that notice.

keefaz · 05-02-2016, 10:30 AM

Quote:

Originally Posted by apss_evaluator

simply the results should be like this:

Why it should be like this? echo'ing a non existent array item leads to unknown, your php setup throws notice on standard out, while in some other configs it will seem to be silent (like in your video) but notice will be seen on server errors log etc...

Imho it isn't good programming practice to print null variable, in some other language, this error could lead to quit program abruptly.

apss_evaluator · 05-02-2016, 10:33 AM

Quote:

Originally Posted by urbanwks

This is the expected output. I tested in PHP 5.5.6 and got the same result. I see what he's trying to prove - that if you unset the variable, then there's nothing to display. That's essentially what you successfully proved by receiving that notice.

Either the instructor has notice reporting turned off somewhere (as keefaz suggested), or perhaps he's using an older version of PHP that doesn't throw the notice. I can't tell you when or if there was a version where this notice wouldn't show up, but I don't remember there ever being a case where what you're trying to do didn't throw that notice.

You're right the instructor is using php 5.0.2, appears to be way back old version. understood it now. thanks :-)