So how big can a $variable in PHP get? I've tried to test this, but I don't have enough system memory (~2gb). I figure there has to be some kind of limit. What happens when a string gets too large? Is it concatenated, or does PHP throw an exception?
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108answers:
3Disk drives have a limit on the size of files they can address. Operating systems have limits on the amount of memory they can keep track of. There are limits on everything.
Rook
2010-07-06 18:24:02
@The Rook nope mcandre lives in a world where computers can address things infinitely. It's also the world where they rule over all humans and Portia de Rossi is the Queen of England.
2010-07-06 18:25:32
@MrXexxed Well of course. I was just reading off of the PHP Manual.
mcandre
2010-07-06 18:30:06
A:
No, the limit is based on your system's available memory. Basically, once your system runs out of memory, it can't add onto the string anymore.
animuson
2010-07-06 18:23:13
+9
A:
There's no architectural limit on a single string variable per se. You can slurp in the contents of an entire file, for instance using file_get_contents()
However, a PHP script has a limit on the total memory it can allocate for all variables in a given script execution, so this effectively places a limit on the length of a single string variable too.
This limit is the memory_limit directive in the php.ini configuration file. The memory limit defaults to 128MB in PHP 5.2, and 8MB in earlier releases.
If you don't specify a memory limit in your php.ini file, it uses the default, which is compiled into the PHP binary. In theory you can modify the source and rebuild PHP to change this default value.
If you specify -1 as the memory limit in your php.ini file, it stop checking and permits your script to use as much memory as the operating system will allocate. This is still a practical limit, but depends on system resources and architecture.
Bill Karwin
2010-07-06 18:32:01