php判断数组问题-php教程-PHP中文網

我想在foreach()循环中只显示没有下级的大栏目（例如只显示代码中的大栏目一,大栏目四），有下级栏目的不显示，如何判断呢？

cid=栏目ID，name=栏目名称，parent_cid=子栏目的上级栏目ID

{"seller_cat":[
{"cid":"1","name":"大栏目一","parent_cid":"0"},
{"cid":"2","name":"大栏目二","parent_cid":"0"},
{"cid":"3","name":"子栏目二","parent_cid":"2"},
{"cid":"4","name":"子栏目三","parent_cid":"2"},
{"cid":"5","name":"大栏目三","parent_cid":"0"},
{"cid":"6","name":"子栏目一","parent_cid":"5"},
{"cid":"7","name":"大栏目四","parent_cid":"0"}
]}}

回复讨论(解决方案)

$s =<<< TXT{"seller_cat":[{"cid":"1","name":"大栏目一","parent_cid":"0"},{"cid":"2","name":"大栏目二","parent_cid":"0"},{"cid":"3","name":"子栏目二","parent_cid":"2"},{"cid":"4","name":"子栏目三","parent_cid":"2"},{"cid":"5","name":"大栏目三","parent_cid":"0"},{"cid":"6","name":"子栏目一","parent_cid":"5"},{"cid":"7","name":"大栏目四","parent_cid":"0"}]}TXT;$a = json_decode($s);foreach($a->seller_cat as $t) {  if($t->parent_cid == 0 && ! array_filter($a->seller_cat, function($v) use ($t) { return $v->parent_cid == $t->cid;}))    echo $t->name;}

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$s =<<< TXT{"seller_cat":[{"cid":"1","name":"大栏目一","parent_cid":"0"},{"cid":"2","name":"大栏目二","parent_cid":"0"},{"cid":"3","name":"子栏目二","parent_cid":"2"},{"cid":"4","name":"子栏目三","parent_cid":"2"},{"cid":"5","name":"大栏目三","parent_cid":"0"},{"cid":"6","name":"子栏目一","parent_cid":"5"},{"cid":"7","name":"大栏目四","parent_cid":"0"}]}TXT;$a = json_decode($s);foreach($a->seller_cat as $t) {  if($t->parent_cid == 0 && ! array_filter($a->seller_cat, function($v) use ($t) { return $v->parent_cid == $t->cid;}))    echo $t->name;}

登入後複製

Parse error: syntax error, unexpected T_FUNCTION in D:\aaa\3.php on line 16

版主大大，你的代码出现这个错误啊

$s =<<< TXT{"seller_cat":[{"cid":"1","name":"大栏目一","parent_cid":"0"},{"cid":"2","name":"大栏目二","parent_cid":"0"},{"cid":"3","name":"子栏目二","parent_cid":"2"},{"cid":"4","name":"子栏目三","parent_cid":"2"},{"cid":"5","name":"大栏目三","parent_cid":"0"},{"cid":"6","name":"子栏目一","parent_cid":"5"},{"cid":"7","name":"大栏目四","parent_cid":"0"}]}TXT;$a = json_decode($s);foreach($a->seller_cat as $t) {  if($t->parent_cid == 0 && ! array_filter($a->seller_cat, function($v) use ($t) { return $v->parent_cid == $t->cid;}))    echo $t->name;}

登入後複製

Parse error: syntax error, unexpected T_FUNCTION in D:\aaa\3.php on line 16

版主大大，你的代码出现这个错误啊

我改了下版主的代码

<?php$s ='{"seller_cat":[{"cid":"1","name":"大栏目一","parent_cid":"0"},{"cid":"2","name":"大栏目二","parent_cid":"0"},{"cid":"3","name":"子栏目二","parent_cid":"2"},{"cid":"4","name":"子栏目三","parent_cid":"2"},{"cid":"5","name":"大栏目三","parent_cid":"0"},{"cid":"6","name":"子栏目一","parent_cid":"5"},{"cid":"7","name":"大栏目四","parent_cid":"0"}]}';$a = json_decode($s,true);foreach($a['seller_cat'] as $t) {  if($t['parent_cid'] == 0 && ! array_filter($a['seller_cat'], function($v) use ($t) { return $v['parent_cid'] == $t['cid'];}))    echo $t['name'];}

登入後複製

$s =<<< TXT{"seller_cat":[{"cid":"1","name":"大栏目一","parent_cid":"0"},{"cid":"2","name":"大栏目二","parent_cid":"0"},{"cid":"3","name":"子栏目二","parent_cid":"2"},{"cid":"4","name":"子栏目三","parent_cid":"2"},{"cid":"5","name":"大栏目三","parent_cid":"0"},{"cid":"6","name":"子栏目一","parent_cid":"5"},{"cid":"7","name":"大栏目四","parent_cid":"0"}]}TXT;$a = json_decode($s);foreach($a->seller_cat as $t) {  if($t->parent_cid == 0 && ! array_filter($a->seller_cat, function($v) use ($t) { return $v->parent_cid == $t->cid;}))    echo $t->name;}

登入後複製

Parse error: syntax error, unexpected T_FUNCTION in D:\aaa\3.php on line 16

版主大大，你的代码出现这个错误啊

版主的代码其实没问题哈~可以跑得起。。你也看看我这个吧~~

闭包从 php5.3 开始支持，现在都 php5.6 了
所以我不能保护落后了

对于php < 5.3 可以用create_function创建匿名函数，不过用create_function 与用eval类似，有安全隐患，且性能低。

foreach($a->seller_cat as $t) {   $func = 'return $x->parent_cid == ' . $t->cid . ';';  if($t->parent_cid == 0 && ! array_filter($a->seller_cat, create_function('$x', $func)))    echo $t->name;}

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你也可以用类来做。

类方法，可以参考下。

$a = json_decode($s);$ar = array();foreach($a->seller_cat as $t) {  if($t->parent_cid == 0 && ! array_filter($a->seller_cat, array(new T($t->cid), 'filter')))    $ar[] = $t->name;}print_r($ar);class T {        private $cid;        function __construct($cid) {                $this->cid = $cid;        }        function filter($v) {                return $v->parent_cid == $this->cid;        }}

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类方法，可以参考下。

$a = json_decode($s);$ar = array();foreach($a->seller_cat as $t) {  if($t->parent_cid == 0 && ! array_filter($a->seller_cat, array(new T($t->cid), 'filter')))    $ar[] = $t->name;}print_r($ar);class T {        private $cid;        function __construct($cid) {                $this->cid = $cid;        }        function filter($v) {                return $v->parent_cid == $this->cid;        }}

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版主大人，用你这个方法可以正常使用了，不过我写漏代码了，你能再帮我看看吗？
代码是这样的，前面的seller_cats我写漏了，加上去就用不了你提供的代码

{"seller_cats":{"@attributes":{"list":"true"},"seller_cat":[
{"cid":"1","name":"大栏目一","parent_cid":"0"},
{"cid":"2","name":"大栏目二","parent_cid":"0"},
{"cid":"3","name":"子栏目二","parent_cid":"2"},
{"cid":"4","name":"子栏目三","parent_cid":"2"},
{"cid":"5","name":"大栏目三","parent_cid":"0"},
{"cid":"6","name":"子栏目一","parent_cid":"5"},
{"cid":"7","name":"大栏目四","parent_cid":"0"}
]}}

$s =<<< TXT{"seller_cat":[{"cid":"1","name":"大栏目一","parent_cid":"0"},{"cid":"2","name":"大栏目二","parent_cid":"0"},{"cid":"3","name":"子栏目二","parent_cid":"2"},{"cid":"4","name":"子栏目三","parent_cid":"2"},{"cid":"5","name":"大栏目三","parent_cid":"0"},{"cid":"6","name":"子栏目一","parent_cid":"5"},{"cid":"7","name":"大栏目四","parent_cid":"0"}]}TXT;$a = json_decode($s);foreach($a->seller_cat as $t) {  if($t->parent_cid == 0 && ! array_filter($a->seller_cat, function($v) use ($t) { return $v->parent_cid == $t->cid;}))    echo $t->name;}

登入後複製

Parse error: syntax error, unexpected T_FUNCTION in D:\aaa\3.php on line 16

版主大大，你的代码出现这个错误啊

版主的代码其实没问题哈~可以跑得起。。你也看看我这个吧~~

我的PHP版本太低了，跑不起这个代码呀

为什么用不了？报什么错误了么？贴出你的代码看看。

foreach($a->seller_cats->seller_cat as $t) {
if($t->parent_cid == 0 && ! array_filter($a->seller_cats->seller_cat, array(new T($t->cid), 'filter')))
$ar[] = $t->name;
}

谢谢jordan102和xuzuning版主大人，问题已经解决了。。。