Anyone know of a library that allows data to be serialized in C++ such that it can be deserialized using the default PHP \'unserialize\' function?
Here is the same question for Java. It should be pretty easy to write your own with examples. PHP its self is written in c and you could modify the deserialize source to your needs.
There are several implementations for other languages here
http://objectmix.com/php/362009-specification-serialize.html#post1335166
The C implementation used by PHP itself is also here:
http://svn.php.net/repository/php/php-src/branches/PHP_5_2/ext/standard/var.c
http://svn.php.net/repository/php/php-src/branches/PHP_5_2/ext/standard/var_unserializer.c
However, unless you're absolutely certain that your choice serialization format is going to be a major bottleneck, consider using a more readily available serialization format, like JSON, XML, Protocol Buffers, or WDDX.
Since you're probably only serializing data, and not PHP objects, you may find a standardized "common ground" serialization more effective. (JSON is likely the simplest)