<?php
$long="big_long_variable_name";
$$long="PHP";     /* 用存放在變量$long里的字符串作為新變量的變量名，等同于$big_long_variable_name="PHP"; */
$short=& $big_long_variable_name;  /* 取變量$big_long_variable_name的值賦給變量$short，此時(shí)$short的值為"PHP"，等同于$short=& $$long; */
print "01 /$short is $short.";   /* "/$"是轉(zhuǎn)義序列，表示輸出一個(gè)美元符號(hào)$，下同。本語句的作用是輸出：01 $short is PHP. */
print "02 Long is $big_long_variable_name."; /* 輸出：02 Long is PHP. */
?>
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<?php $big_long_variable_name.=" rocks!"; /* 重新對(duì)$big_long_variable_name賦值。重新賦值過程中，由于在$big_long_variable_name的后面添加了.（點(diǎn)號(hào)），因而變量$big_long_variable_name此時(shí)的值應(yīng)為原值（"PHP"）+新值（" rocks!"），即變量$big_long_variable_name當(dāng)前完整的值為"PHP rocks!"。下同。*/
print "03 /$short is $short";   /* 輸出：03 $short is PHP rocks! */
print "04 Long is $big_long_variable_name"; /* 輸出：04 Long is PHP rocks! */
?>
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05 $short is PHP rocks!
06 Long is PHP rocks!
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<?php $short.="Programming $short";   /* 重新對(duì)變量$short賦值。由于在$short后面添加了.（點(diǎn)號(hào)），因此請(qǐng)參考上例分析$short的值。*/
print "07 /$short is $short";   /* 輸出：07 $short is PHP rocks!Programming PHP rocks! */
print "08 Long is $big_long_variable_name"; /* 由于變量$short被重新賦值為Programming PHP rocks!，因而變量$big_long_variable_name的值也與$short一同被改變?yōu)?PHP rocks!Programming PHP rocks!"。本語句輸出：08 Long is PHP rocks!Programming PHP rocks!注意，如果是對(duì)具有相同值的一個(gè)變量進(jìn)行銷毀unset( )，則另一個(gè)變量不適用于此種情況，即不會(huì)隨之被一同銷毀。*/
?>
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09 $short is Programming PHP rocks!
10 Long is Programming PHP rocks!
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<?php $big_long_variable_name.="Web Programming $short";  /* 變量$big_long_variable_name被重新賦值，此時(shí)它完整的值應(yīng)為PHP rocks!Programming PHP rocks!Web Programming PHP rocks!Programming PHP rocks!。變量$short的值此時(shí)與變量$big_long_variable_name一致。請(qǐng)分別參考第5處、第10處注釋進(jìn)行分析。*/
print "11 /$short is $short";     /* 輸出：11 PHP rocks!Programming PHP rocks!Web Programming PHP rocks!Programming PHP rocks! */
print "12 Long is $big_long_variable_name";
?>
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<?php
unset($big_long_variable_name);   /* 用unset( )銷毀變量$big_long_variable_name，變量$short不會(huì)因此受到任何影響。*/
print "13 /$short is $short";   /* 雖然銷毀了變量$big_long_variable_name，但$short沒有受到影響，它的值仍是最近一次被賦予的PHP rocks!Programming PHP rocks!Web Programming PHP rocks!Programming PHP rocks! */
print "14 Long is $big_long_variable_name."; /* 變量$big_long_variable_name已被銷毀，故而無值。輸出：14 Long is. */
snow;                                   
?>
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<?php $short="No point TEST1";   /* 重新對(duì)變量$short賦值。由于這次沒有在$short后面添加.（點(diǎn)號(hào)），因此$short當(dāng)前的值為"No point TEST1"。*/
print "15 /$short is $short.";   /* 輸出：15 $short is No point TEST1. */
$short="No point TEST2 $short";   /* 重新對(duì)變量$short賦值。沒在$short的后面添加.（點(diǎn)號(hào)），但引用了它自身最近一次的值"No point TEST1"。*/
print "16 /$short is $short.";   /* 輸出：16 $short is No point TEST2 No point TEST1. */