Regular Expression-Remove irregular spaces in PHP Regular Expression matching

{Code...} writing a regular expression can match all the results that can only be composed of & quot; p & quot; + numbers. How can I write {code?

$ Str = "ac p1 p4 p0 fe p6 p8 p9 p10 p11 ap7 p3d p12 ";

Write a regular expression to match all"P" + numberCombination

The result is as follows:

P1 p4 p0 p6 p8 p9 p10 p11 p12

How to write?

Reply content:

$ Str = "ac p1 p4 p0 fe p6 p8 p9 p10 p11 ap7 p3d p12 ";

Write a regular expression to match all"P" + numberCombination

The result is as follows:

P1 p4 p0 p6 p8 p9 p10 p11 p12

How to write?