1 $apple   =   ' apple ' ;
2 print   $apple ;
3 $orange   =   & $apple ;
4 $orange   =   ' orange ' ;
5 echo   ' <br> ' ;
6 print   $apple ;
7 echo   " <br> " ;

题目二：

Create a second class, Test2, with exactly the same capability as 
Test1 except that the print_variables function can optionally be 
supplied a parameter that will either cause the output to be:
Var1 = XX, Var2 = YY (This should be the default case)
OR
Var2 = YY, Var1 = XX

Show code for creating objects of each class and then calling the 
print_variables function of each object with all supported parameters.

翻译：太简单了..自己看

解决思想：
PHP类属性的使用

答案：

 1 class  Test2 
 2 {
 3      private   $var1 ;
 4      private   $var2 ;
 5      function  __construct( $var1 = ' XX ' , $var2 = ' YY ' )
 6     {
 7          $this -> var1  =   $var1 ;
 8          $this -> var2  =   $var2 ;
 9     }
10
11      public   function  print_variables()
12     {
13          print ( ' Var1 =  ' . $this -> var1 . ' ,Var2 =  ' . $this -> var2);
14     }
15     
16 }
17
18 $test   =   new  Test2();
19 $test -> print_variables();
20
21 unset ( $test );
22 echo   " <br> " ;
23
24 $test   =   new  Test2( " YY " , " XX " );
25 $test -> print_variables();
26
27 unset ( $test );
28 echo   " <br> " ;
29

题目三：
Create a class, Test3, with the following behavior:
The class must take a string of the format 
name1=value1:name2=value2:name3=value3 consisting of name and value 
pairs, separated by the : symbol. I must be able to enter as many 
pairs as I like when I call the class, the only limit is that each 
pair is formated as name=value and multiple pairs are separated by 
the : symbol.
When an object of the class is created it must end up with a variable 
for each name=value pair. The name of the variable must be the same 
as the name part of the substring and the value of the variable must 
be the same as the value part of the substring. For example:

creating an object with new Test3("firstname=david:lastname=smith") 
must create variables within the class:
$firstname = "david";
$lastname = "smith";

and new Test3("food1=pasta:food2=chocolate") must create variables 
within the class:
$food1 = "pasta";
$food2 = "chocolate";

I should be able to use any variable names and values provided they 
do not include the symbols : or =

You should then write a function print_all that will print the all 
the names of the defined variables in the class along with their 
values in the following format:
Variable 1 - Name = (whatever the actual name is), Value = (whatever 
the actual value is)
Variable 2 - Name = (whatever the actual name is), Value = (whatever 
the actual value is)
Variable 3 - Name = (whatever the actual name is), Value = (whatever 
the actual value is)
and so on until all the variables are listed.

The last line of output of the print_all function should be the words 
"The original input was " followed by a string that is an exact 
representation of the string parameter supplied when creating the 
class object.

For example, if you did new Test3("firstname=david:lastname=smith") 
then the print_all function should output:

Variable 1 - Name = firstname, Value = david
Variable 2 - Name = lastname, Value = smith
The original imput was ("firstname=david:lastname=smith")

This must work for any input string that has the correct format and 
you may not store the complete input string or directly output it to 
produce the last line of the print_all function output as that would 
be too easy.

暂时没做，稍后放出答案