I'm a beginner in php. I don't know how to explain this program.

I am a beginner in php. I do not understand this program. & lt; html & gt; & nbsp; & lt; head & gt; & nbsp; & lt; title & gt; test & lt;/title & gt; & nbsp; & lt; body & gt; & lt ;? Phpfunct I am a beginner in php. I don't understand this program.

 
Test
 
Function dealdata (& $ value, & $ key)
{
$ Value. = "123 ";
$ Key. = "456 ";
$ Cnt ++;
}

$ Cnt = 0;
$ States = array ("a" => "aa", "B" => "bb", "c" => "cc ");

Echo $ cnt ."
";
Print_r ($ states );

Array_walk ($ states, "dealdata ");

Echo $ cnt ."
";
Print_r ($ states );

?>
 
 
 
 
Question 1: I think $ cnt is global, so I think cnt should be 3 (I learned C ++ before)
Question 2: Why is the key unchanged when the $ states value changes? I have changed both key and value?
The more detailed the information, the better.
------ Solution --------------------
Question 1
Yes, $ cnt is global, but you change its value in the function. it is valid only in the function and is invalid outside the function.

Question 2
You can only modify the value of array_walk to see the manual.

------ Solution --------------------
Question 1: I think $ cnt is global, so I think cnt should be 3 (I learned C ++ before)
Unlike C ++, php shields all external variables in functions.
If an external variable is used in a function, a global statement is required.

Question 2: Why is the key unchanged when the $ states value changes? I have changed both key and value?
The structure of the host cannot be changed in array_walk.
Changing the key is about changing the structure, so it is not allowed.
Changing the value is only valid when the reference is passed.