Php if($var) used to work [closed]

问题

I have som code for a website, that used to work fine with. I want to check if a variable or session is set. I used the following code:

if ($_GET['something']){ //Do something }

Now i try to install it on a local server, at i get a error code, saying that there is an undefined index.

It requires me to do:

if (isset($_GET['']) { //Do something }

Can i make a quick fix for this, as i don't want to change the code so many places?

回答1:

You didn't get the error before, because your error_reporting and/or display_error settings were set too forgiving. Your first snippet is attempting to access a value in an array that might not exist. If it doesn't PHP always issues a notice.
It's only after the notice has been issued that it can be hushed up (by turning off display_errors or setting error_reporting to not report notices (~E_NOTICE).

You're asking for a quick fix:

if (isset($_GET['something']))

only requires you to add isset(). That's quick, and it fixes the issue. Besides: using isset is what you should do. Always.

Off-topic, but perhaps useful:
As I've explained in the comments: the best course of action for you now is to fix the issue itself, not ignoring the notices. To that end, a simple script that scans your projects directories for .php files (using glob), reads them in and looks for a pattern might prove useful:

foreach ($phpFiles as $file)
{
    $code = file_get_contents($file);//read the file
    if (preg_match_all('/if\s*\(\$[^[]+\[[^]]+\]\s*\)/',$code, $matches))
    {//find all usages of "if ($rawVar['offset'])" in code
        echo 'Expressions to check or fix in file: ', $file,':', PHP_EOL, '=>';
        echo implode(PHP_EOL.'=>', $matches[0]), PHP_EOL;
    }
}

run the script, perhaps write the output to a temp file, and set to work. The output should look something like:

Expressions to check or fix in file: scriptname.php:
=> if ($_GET['something'])
=> if ($var[123])

And so on. It's a workable format, and given time, you might be able to write a script for you to automatically refactor the code, too.
Perhaps a more comprehensive (as in complete) regex to use here would be something like:

/if\s*\((\|\||&&|\()?\$[^[]+\[[^]]+\]\s*(\|\||&&|\))?/

But this, too, has some caveats still, but it's a start.

Adding assignments - I'll do you one more favour: adding code that fixes the issues you get in assignment expressions like $var = $_GET['something'];. This can be done automatically, and quite easily, too:

foreach ($phpFiles as $file)
{
    $code = file_get_contents($file);//read the file
    $clean = preg_replace(
        '/(\$[^\s]+\s*={1}\s*)(\$[^[]+[^]]+\])\s*;/',
        '$1isset($2) ? $2 : null;',
        $code
    );
    file_put_contents($file, $clean);
}

I've tested this code like so:

$code = '$foo = 123;
$foo = $_GET["bar"];';
$clean = preg_replace(
    '/(\$[^\s]+\s*={1}\s*)(\$[^[]+[^]]+\])\s*;/',
    '$1isset($2) ? $2 : null;',
    $code
);
echo $clean, PHP_EOL;

And it yielded the expected output:

$foo = 123;
$foo = isset($_GET["bar"]) ? $_GET["bar"] : null;

Combine these two regex's and you should be well on your way to refactoring the code you have...

回答2:

Check whether you are having the parameter

something

if it is not, then pass some dummy values to check.

回答3:

There are two ways fix it or hide it.

First option is better and can be done with isset() function and it's the best solution.

Another way is to hide notice errors you can do it with error_reporting(E_ALL & ~E_NOTICE); I don't recommend this solution

回答4:

Will work without notices if you have value of $_GET['something'] on when checking or it's already defined. Also you have error reporting on on your local server not on second server so giving you notices on local server.

if ($_GET['something']){

if not defined you need to use isset() or empty() to avoid php notices.

if (isset($_GET['something'])){ // will check variable is already set
if (!empty($_GET['something'])){ // will check variable value is not blank or 0

or you need to initialize a variable with blank or with some predefined values.

回答5:

use this may be it helps if(isset(@$_GET[''])){ }

来源：https://stackoverflow.com/questions/26234036/php-ifvar-used-to-work

标签

php

if-statement

isset