Big Brother and sister of php, help me solve a problem

Php's big brother and sister, help me solve a problem. I have a variable: $ strDate. the variable value may be or... it cannot be any day of all time. now I want to return the month in which the value is changed. that is to say, the month of the specified date is returned. when $ strDate = 2012-08-06 is returned: 8 when $ php's big sisters help me solve a problem
I have a variable: $ strDate, which may be or... not necessarily any day of all time,
Now I want to return the month in which the value is changed.

That is, the month of the specified date is returned,

If $ strDate = 2012-08-06 is returned: 8
If $ strDate = 2010-02-06 is returned: 2
If $ strDate = is returned: 8
If $ strDate = is returned: 8

What is this function '>?

------ Solution --------------------
Echo date ('N', strtotime ($ strDate ));