数组函数学习小结

<?php
    // array_udiff用回调函数比较数据来计算数组的差集
    // 要对比的数组
    $array1 = array(new stdclass, new stdclass,
                new stdclass, new stdclass,
               );
    $array2 = array(
                new stdclass, new stdclass,
               );
    // 为每个对象设置一些属性
    $array1[0]->width = 11; $array1[0]->height = 3;
    $array1[1]->width = 7;  $array1[1]->height = 1;
    $array1[2]->width = 2;  $array1[2]->height = 9;
    $array1[3]->width = 5;  $array1[3]->height = 7;
    $array2[0]->width = 7;  $array2[0]->height = 5;
    $array2[1]->width = 9;  $array2[1]->height = 2;
    function compare_by_area($a, $b) {
        $areaA = $a->width * $a->height;
        $areaB = $b->width * $b->height;
        if ($areaA < $areaB) {
            return -1;
        } elseif ($areaA > $areaB) {
            return 1;
        } else {
            return 0;
        }
    }
    $array3=array_udiff($array1, $array2, 'compare_by_area');
    printf('<pre>%s</pre>',print_r($array3,true));
    echo '<hr>';
    // array_reverse — 返回单元顺序相反的数组
    $input  = array("php", 4.0, array("green", "red"));
    $reversed = array_reverse($input);
    $preserved = array_reverse($input, true);//true保持原有的key值,默认为false
    printf('<pre>%s</pre>',print_r($input,true));
    printf('<pre>%s</pre>',print_r($reversed,true));
    printf('<pre>%s</pre>',print_r($preserved,true));
    echo '<hr>';
    // array_intersect_uassoc — 带索引检查计算数组的交集，用回调函数比较索引
    $array1 = array("a" => "green", "b" => "brown", "c" => "blue", "red");
    $array2 = array("a" => "GREEN", "B" => "brown", "yellow", "red");
    printf('<pre>%s</pre>',print_r(array_intersect_uassoc($array1, $array2, "strcasecmp"),true));
    echo '<hr>';
    // array_walk_recursive — 对数组中的每个成员递归地应用用户函数
    $sweet = array('a' => 'apple', 'b' => 'banana');
    $fruits = array('sweet' => $sweet, 'sour' => 'lemon');
    function test_print($item, $key)
    {
        echo "$key holds $item <br>";
    }
    array_walk_recursive($fruits, 'test_print');
    echo '<hr>';
    // array_uintersect — 计算数组的交集，用回调函数比较数据
    $array5 = array("a" => "green", "b" => "brown", "c" => "blue", "red");
    $array4 = array("a" => "GREEN", "B" => "brown", "yellow", "red");
    printf('<pre>%s</pre>',print_r(array_uintersect($array5, $array4, "strcasecmp"),true));

效果：