[RESOLVED] Single quoted string not equal to identical double quoted string?

Myth_UK_

Hi, this is my first post on this forum.

I haven't used PHP since 2007, so I am a bit rusty, but I have come across a strange bug. I am running php 5.2 Non Thread Safe on Windows IIS on vista.

Problem is when using single quotes.

if ('hello' == "hello") This returns false

echo stren('hello'); This returns 7

BUT if I do this:- echo strlen("hello"); (which returns 5)

THEN do echo stlen('hello'); (with the single quotes again, returns 5);

AND if ('hello' == "hello") Now returns true;

P.S The mbstring.func_overload is OFF in my php.ini

laserlight

This sounds very strange indeed. Post the smallest and simplest script that demonstrates the problem. You should also consider checking your source with a hex editor for any non-printable characters.

halojoy

if ('hello' == "hello") This returns false
Because they are 2 different strings!

Separate the quotes:
I am quite sure, you have written:
' ' h e l l o ' ' = 7 chars inside quote
not
" h e l l o " = 5 chars inside quote

2 single quotes '' is not the same as one double quote "
They are 2 different keys on your keyboard

First case should return true:

if ('hello' == "hello")
    echo 'true';
else
    echo 'false';

echo '<hr>';

if ('hello' == "'hello'")
    echo 'true';
else
    echo 'false';

laserlight

halojoy wrote:
Separate the quotes:
I am quite sure, you have written:
' ' h e l l o ' ' = 7 chars inside quote
not
" h e l l o " = 5 chars inside quote

That sounds unlikely to me because it should result in a parse error.

Myth_UK_

example:

function test ($string) {

echo strlen($string);

echo strlen(trim($string);

}

echo strlen('48hours.'); result 8

echo test('48hours.'); result 32 and 10

echo test("48hours."); result 8 and 8

run single quotes again...

echo test('48hours.'); result 8 and 8

Help!

laserlight

Next time, post PHP code in [noparse]

[/noparse] bbcode tags. Copy and paste the code that you actually ran.

I see no reason why the output will be as you described. Maybe it is some kind of character encoding problem that I have never encountered. What do you see when you view your source code in a hex editor?

Myth_UK_

I just use notepad, no hex editor.

<?php
// Cryptography Fuction
// Parameter: $string = The string that you want to encrypt / decrypt.
// Parameter: $key = encryption key.
// Parameter: $command = true to encrypt, false to decrypt. 
// Returns: The encrypted / decrypted string;
function encryptDecrypt ($string, $key, $command) {
$algorithm = mcrypt_module_open('rijndael-256', '', 'ecb', '');
$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($algorithm), MCRYPT_RAND);
$key = substr($key, 0, mcrypt_enc_get_key_size($algorithm));
mcrypt_generic_init($algorithm, $key, $iv);
if($command) {
$string = trim($string);
$stringLength = strlen($string);

echo $stringLength; // JUST TO SHOW THE DIFFERENCE

$string = $stringLength . '|' .$string;
$encryptedData = mcrypt_generic($algorithm, $string);
} else {
$encryptedData = mdecrypt_generic($algorithm, $string);
list($stringLength, $paddedData) = explode('|', $encryptedData, 2);
$encryptedData = substr($paddedData, 0, $stringLength);
}
mcrypt_generic_deinit($algorithm);
mcrypt_module_close($algorithm);   

return $encryptedData;
}

encryptDecrypt('hello world', $cryptKey, true); // Call function single quotes

encryptDecrypt("hello world", $cryptKey, true); // Call function double quotes

if (encryptDecrypt('hello world', $cryptKey, true) == encryptDecrypt("hello world", $cryptKey, true)) {
echo "Match";
} else {
echo "Dont Match";
}
?>

Output: 13 for single quotes
Output: 11 for double quotes
Output: Dont Match

laserlight

Myth(UK) wrote:
I just use notepad, no hex editor.

There are a few available at zero price. I use xvi32 on Windows.

Myth(UK) wrote:
Output: 13 for single quotes
Output: 11 for double quotes
Output: Dont Match

After adding:

$cryptKey = 'abcd';

I get the output:

11111111Match

This is with PHP 5.3.1 running as an Apache 2.2 module on Windows 7.

Myth_UK_

Yes, that is what you should get...

But thats my problem, I don't.

I am running php 5.2, on IIS 7... I think it must be a bug, but I don't know what to do about it.

It's almost as if the single quote strings are being padded out, is there some quirky feature in the php.ini that does this or is it a know bug in 5.2... or is it just mu luck? 😕

P.S will use the php tags in future, it's my first time here :o

laserlight

It is not likely to be a bug with PHP 5.2, otherwise it would be well known. Anyway, I quickly switched to PHP 5.2.11 and can confirm that I still cannot reproduce the problem.

Myth_UK_

Just an update on the situation.

Running my function on its own, (outside the rest of my code), yielded the correct results.

So, I went through the rest of my code line by line looking for errors, even though the error log showed no errors.

Couldn’t find a problem, so replaced the function back into the main program, and it worked!!!

Rebooted my PC twice, and the code functioned perfectly each time. Note: (The code has not been altered from my first post. It seems to work some of the time, but not all of the time... This has to be a bug. (I will keep an eye on the results over the next few days). It may be a problem with using a none thread safe version on windows?

Thanks for your help. :rolleyes:

Myth_UK_

The above function is called before I send any headers, i.e. before I output:

header('Content-type: text/html; charset=iso-8859-1');

to the browser. Would this cause a problem with how php handles strings? Does it need to know the character set I am using before doing any string manipulation. I know php is supposed to treat all strings as single byte characters, so I shouldn't matter.

P.S A colleague mentioned that FastCGI is quite broken on IIS, and he thinks this could be one of the many problems with it.?

I normally write C++, C# apps... but I have written websites in PHP about 3-4 years ago, and never had this sort of problem. At the moment, the code is working perfectly, the problem is I haven't altered it from when it wasn't. :glare:

laserlight

Since the characters that you are using are within ASCII, iso-8859-1 should not pose a problem in any case.

Must you use IIS? Perhaps you should try Apache and see if your problem persists.

Myth_UK_

I used to use Apache myself, but at work I am stuck with IIS because they only write for ASP.Net, and the IT department won't allow me to install Apache for this one off.

Myth_UK_

After downloading the Hex editor, I did indeed find some none printable characters in the source. Some one had pasted a unicode string in one of the include files.

This has now been fixed. But I am not sure this caused the original problem, but at the moment, everything seems fine.

Thanks laserlight for your help... fingers crossed 😃