PHP file_exists() anomaly

问题

i ran into this wierd problem: the $myImg variable has been extracted from some local html and points to a file i would like to check. With the string variable file_exists gives false, but if the content os variable is inserted manually it gives true.

var_dump($myImg);

outputs: string(26) "content/images/1107_16.jpg"

var_dump(file_exists($myImg));

outputs: bool(false)

var_dump(file_exists("content/images/1107_16.jpg"));

outputs: bool(true)

How could it happen? Thanks for any help in advance

回答1:

Try converting the string before passing it to file_exists method

$myImg = mb_convert_encoding($myImg, "UTF-8");

Additionally, you can always trim the other unwanted characters attached to the dirty string.

回答2:

The length of content/images/1107_16.jpg is not 45, so obviously there are other characters. Try trimming the variable.

回答3:

riad@riad-desktop:~$ php -r 'print(strlen("content/images/1107_16.jpg"));'
26

So, Your string is bad (maybe consist of a bad characters (\0 ?) on the end

回答4:

I offer you to compare the results using bin2hex():

var_dump(bin2hex($myImg));
var_dump(bin2hex("content/images/1107_16.jpg"));

It seems that it's the problem of different charsets.

回答5:

perhaps some invisible character in your $myImg? something like a line break?

回答6:

You seem to be have some unprintable characters in your string, or a different character encoding:

var_dump ("content/images/1107_16.jpg");
string(26) "content/images/1107_16.jpg"

Note that this correctly reports 26 bytes - which would be right with ASCII (or UTF-8). The 45 bytes reported above would sem like some sort of multibyte encoding.

回答7:

string(45) "content/images/1107_16.jpg" 

should be less chars long try :

trim($myImg)

to remove spacechars

来源：https://stackoverflow.com/questions/6676295/php-file-exists-anomaly