用PHP迭代器来实现一个斐波纳契数列

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/**

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* @author 简明现代魔法 http://www.nowamagic.net

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*/

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class

Fibonacci

implements

Iterator {

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private

$previous

=1;

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private

$current

=0;

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private

$key

=0;

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public

function

current() {

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return

$this

->current;

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}

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public

function

key() {

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return

$this

->key;

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}

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public

function

next() {

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// 关键在这里

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// 将当前值保存到 $newprevious

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$newprevious

=

$this

->current;

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// 将上一个值与当前值的和赋给当前值

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$this

->current +=

$this

->previous;

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// 前一个当前值赋给上一个值

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$this

->previous =

$newprevious

;

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$this

->key++;

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}

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public

function

rewind

() {

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$this

->previous =1;

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$this

->current =0;

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$this

->key =0;

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}

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public

function

valid() {

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return

true;

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}

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}

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$seq

=

new

Fibonacci;

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$i

=0;

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foreach

(

$seq

as

$f

) {

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echo

"$f "

;

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if

(

$i

++ ===15) 

break

;

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}

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