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关于常见PHP数组排序方法总结_PHP教程

WBOY
WBOY原創
2016-07-15 13:28:01822瀏覽

随着PHP的快速发展,用它的人越来越多,在PHP数组学习摘录部分了解到最基本的PHP数组的建立和数组元素的显示。需要深入学习下PHP数组的相关操作。首先接触的就是PHP数组排序、降序的排序问题。

快速创建数组的函数range()

<ol class="dp-xml">
<li class="alt"><span><span>比如range()函数可以快速创建从1到9的数字数组:  </span></span></li>
<li class="">
<span></span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">php</span></font></strong><span> </span>
</li>
<li class="alt">
<span>$</span><span class="attribute"><font color="#ff0000">numbers</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">range</font></span><span>(1,9);  </span>
</li>
<li class=""><span>echo $numbers[1];  </span></li>
<li class="alt">
<span></span><span class="tag"><strong><font color="#006699">?></font></strong></span><span> </span>
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</ol>

当然,使用range(9,1)则创建了9到1的数字数组。同时,range()还可以创建从a到z 的字符数组:

<ol class="dp-xml">
<li class="alt"><span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">php</span></font></strong><span> </span></span></li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">numbers</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">range</font></span><span>(a,z);  </span>
</li>
<li class="alt"><span>foreach ($numbers as $mychrs)  </span></li>
<li class=""><span>echo $mychrs." ";  </span></li>
<li class="alt">
<span></span><span class="tag"><strong><font color="#006699">?></font></strong></span><span> </span>
</li>
</ol>

使用字符数组时注意大小写,比如range(A,z)和range(a,Z)是不一样的。range()函数还具有第三个参数,该参数的作用是设定步长,比如range(1,9,3)创建的数组元素是:1、4、7。常见PHP数组排序一般数组中的各元素均以字符或数字表现的,所以可对数组元素进行升序排列,该功能函数为sort()。比如:
<ol class="dp-xml">
<li class="alt"><span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">php</span></font></strong><span> </span></span></li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">people</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">array</font></span><span>('name','sex','nation','birth');  </span>
</li>
<li class="alt"><span>foreach ($people as $mychrs)  </span></li>
<li class=""><span>echo $mychrs." ";  </span></li>
<li class="alt"><span>sort($people);  </span></li>
<li class="">
<span>echo "</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span></span></font></strong><span> </span><span class="tag"><strong><font color="#006699">/></font></strong></span><span>---排序后---</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span></span></font></strong><span> </span><span class="tag"><strong><font color="#006699">/></font></strong></span><span>";  </span>
</li>
<li class="alt"><span>foreach ($people as $mychrs)  </span></li>
<li class=""><span>echo $mychrs." ";  </span></li>
<li class="alt">
<span></span><span class="tag"><strong><font color="#006699">?></font></strong></span><span> </span>
</li>
</ol>

升序排序后的数组元素显示为 birth name nation sex,当然,sort()函数是区分字母大小写的(字母从大到小的顺序是:A…Z…a…z)

Sort()函数还具有第二参数,用来说明PHP数组排序升序的规则是用来比较数字还是字符串的。比如:

<ol class="dp-xml">
<li class="alt"><span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">php</span></font></strong><span> </span></span></li>
<li class="">
<span>echo "---按数字升序排序---</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span></span></font></strong><span> </span><span class="tag"><strong><font color="#006699">/></font></strong></span><span>";  </span>
</li>
<li class="alt">
<span>$</span><span class="attribute"><font color="#ff0000">num2</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">array</font></span><span>('26','3',);  </span>
</li>
<li class=""><span>sort($num2,SORT_NUMERIC);  </span></li>
<li class="alt"><span>foreach ($num2 as $mychrs)  </span></li>
<li class=""><span>echo $mychrs." ";  </span></li>
<li class="alt">
<span>echo "</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span></span></font></strong><span> </span><span class="tag"><strong><font color="#006699">/></font></strong></span><span>---按字符升序排序---</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span></span></font></strong><span> </span><span class="tag"><strong><font color="#006699">/></font></strong></span><span>";  </span>
</li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">num3</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">array</font></span><span>('26','3');  </span>
</li>
<li class="alt"><span>sort($num3,SORT_STRING);  </span></li>
<li class=""><span>foreach ($num3 as $mychrs)  </span></li>
<li class="alt"><span>echo $mychrs." ";  </span></li>
<li class="">
<span></span><span class="tag"><strong><font color="#006699">?></font></strong></span><span> </span>
</li>
</ol>

SORT_NUMERIC和SORT_STRING用来声明按数字或字符的升序排列。如果按照数字升序排列是:3,26;但如果按照字符升序排列则是:26,3了。PHP中除了升序函数以外,还有降序或称反向排列的函数,就是rsort()函数,比如:$num1=range(1,9);rsort($num1);这里其实就相当于range(9,1)。


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