关于常见PHP数组排序方法总结

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()

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<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>
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<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>
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<li class=""><span>echo $numbers[1];  </span></li>
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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：

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<span>$</span><span class="attribute"><font color="#ff0000">numbers</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">range</font></span><span>(a,z);  </span>
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<li class="alt"><span>foreach ($numbers as $mychrs)  </span></li>
<li class=""><span>echo $mychrs." ";  </span></li>
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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：

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<span>$</span><span class="attribute"><font color="#ff0000">people</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">array</font></span><span>('name','sex','nation','birth');  </span>
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<li class="alt"><span>foreach ($people as $mychrs)  </span></li>
<li class=""><span>echo $mychrs." ";  </span></li>
<li class="alt"><span>sort($people);  </span></li>
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<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>
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<li class="alt"><span>foreach ($people as $mychrs)  </span></li>
<li class=""><span>echo $mychrs." ";  </span></li>
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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：

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<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>
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<span>$</span><span class="attribute"><font color="#ff0000">num2</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">array</font></span><span>('26','3',);  </span>
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<li class=""><span>sort($num2,SORT_NUMERIC);  </span></li>
<li class="alt"><span>foreach ($num2 as $mychrs)  </span></li>
<li class=""><span>echo $mychrs." ";  </span></li>
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<span>echo "</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span></span></font></strong><span> </span><span class="tag"><strong><font color="#006699">/></font></strong></span><span>---按字符升序排序---</span><strong><font color="#006699"><span class="tag"><span class="tag-name">br</span></span></font></strong><span> </span><span class="tag"><strong><font color="#006699">/></font></strong></span><span>";  </span>
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<span>$</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>
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<li class="alt"><span>sort($num3,SORT_STRING);  </span></li>
<li class=""><span>foreach ($num3 as $mychrs)  </span></li>
<li class="alt"><span>echo $mychrs." ";  </span></li>
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SORT_NUMERIC和SORT_STRING用来声明按数字或字符的升序排列。如果按照数字升序排列是：3，26；但如果按照字符升序排列则是：26，3了。PHP中除了升序函数以外，还有降序或称反向排列的函数，就是rsort()函数，比如：$num1=range(1,9);rsort($num1);这里其实就相当于range(9,1)。