"Example 2. Execute a prepared statement with an array of insert values" demonstrates how to pass an input array. 

Writing about how bindParam takes 1-based indexes for arguments, while the input array to PDOStatement::execute() takes a 0-based index, is just going to confuse users. Less is more, and examples rule.

Example 2 contains only associative array vs named parameters, so it doesn't show how indexes of '?' are handled.

The only example that uses '?' placeholders is #3, which uses bindParam starting from 1.

I find these examples irrelevant to the case, if not confusing.

This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.

Example 2 is now "Example 2. Execute a prepared statement with an array of insert values (named parameters)".

To address your concern, I added another example: "Example 3. Execute a prepared statement with an array of insert values (placeholders)".