Php implementation recent browsing problems

Php implementation of the latest browsing problem functionproduct_view ($ pdid) // What is the value represented by the parameters in this function {$ limit = 8; if (is_numeric ($ pdid) & amp; & amp; $ pdid & lt; & gt; 0) {if (! $ _ SE php implementation of recent browsing problems
Function product_view ($ pdid) // What are the values of parameters in this function?
{
$ Limit = 8; if (is_numeric ($ pdid) & $ pdid <> 0)
{
If (! $ _ SESSION ['PD _ viewed'])
{
$ _ SESSION ['PD _ viewed'] = array ($ pdid );
}
Else
{
If (count ($ _ SESSION ['PD _ viewed '])> = $ limit)
{If (! In_array ($ pdid, $ _ SESSION ['PD _ viewed'])
{
$ _ SESSION ['PD _ viewed '] = array_reverse ($ _ SESSION ['PD _ viewed']);
Array_pop ($ _ SESSION ['PD _ viewed']);
$ _ SESSION ['PD _ viewed'] [] = $ pdid;
$ _ SESSION ['PD _ viewed '] = array_reverse ($ _ SESSION ['PD _ viewed']);
}
}
Else
{
If (! In_array ($ pdid, $ _ SESSION ['PD _ viewed'])
{$ _ SESSION ['PD _ viewed'] [] = $ pdid;
}
}
}
}
}
Please help me explain this program in detail. I don't know much about it. what are the variables in the session?

------ Solution --------------------
These things need to be parsed in conjunction with the entire system.

The pdid should be the product number, so the automatic number in the database or the number of the custom product itself is unclear.

The session is to add the viewed numbers to the array pd_viewed.





Finally, you seem to have posted a lot of posts but none of them are closed. if you continue to do so, no one will answer your questions. if you do not know how to fix the posts, go to the community to help you.
------ Solution --------------------
Function product_view ($ pdid) // $ pdid the column number currently in use
{
$ Limit = 8; // specify the maximum capacity
If (is_numeric ($ pdid) & $ pdid <> 0) // $ pdid is a number and is not 0
{
If (! $ _ SESSION ['PD _ viewed ']) // if it has never been saved
{
$ _ SESSION ['PD _ viewed '] = array ($ pdid); // Save
}
Else
{// Otherwise, insert it to the front of the array.
If (count ($ _ SESSION ['PD _ viewed '])> = $ limit)
{If (! In_array ($ pdid, $ _ SESSION ['PD _ viewed'])
{// The following code only requires writing array_unshift ($ _ SESSION ['PD _ viewed'], $ pdid );
$ _ SESSION ['PD _ viewed '] = array_reverse ($ _ SESSION ['PD _ viewed']);
Array_pop ($ _ SESSION ['PD _ viewed']);
$ _ SESSION ['PD _ viewed'] [] = $ pdid;
$ _ SESSION ['PD _ viewed '] = array_reverse ($ _ SESSION ['PD _ viewed']);
}
}
Else
{
If (! In_array ($ pdid, $ _ SESSION ['PD _ viewed'])
{$ _ SESSION ['PD _ viewed'] [] = $ pdid;
}
}
}
}
}