On the Exakat blog they have a new post with the results from their evaluation of a wide range of PHP applications showing the Top 100 PHP functions in use.
Here is the top 100 PHP functions : it is the list of the most often used PHP native functions.
The functions are named, and ranked from 1 to 100. The other 4500 functions are not ranked now. The frequency column represents how often this function is used across PHP code : the reference corpus is a list of 1900 PHP open source projects. They were audited with Exakat static analysis engine, version 1.2.5. The average is the number of time a function is called within one project. Some function are used in isolation, and others are a staple.
The top 5 on the list are:
Each item on the list comes with "frequency" and "average" scores (that mostly relate directly). Check out the post for the full list and a list of some insights they worked up as they generated the listing.