Gets a prefixed unique identifier based on the current time in microseconds.
Can be useful, for instance, if you generate identifiers simultaneously on several hosts that might happen to generate the identifier at the same microsecond.
With an empty
prefix, the returned string will
be 13 characters long. If
TRUE, it will be 23 characters.
If set to TRUE, uniqid() will add additional entropy (using the combined linear congruential generator) at the end of the return value, which should make the results more unique.
If you need a unique identifier or token and you intend to give out that token to the user via the network (i.e. session cookies), it is recommended that you use something along these lines:
This will create a 32 character identifier (a 128 bit hex number) that is extremely difficult to predict.