简体中文
简体中文
在 PHP 中，is_array() 是判断某个变量是否为数组的最直接内置函数。但“数组元素的结构是否符合预期”通常不仅仅是判断变量是数组，还需要检查数组的键（keys）、值的类型、是否存在必需字段、嵌套结构是否正确等。本篇文章从基础到进阶、配合代码示例，系统讲解如何使用 is_array() 配合其他手段来验证数组结构，并给出常见场景和最佳实践。
is_array($v)：判断 $v 是否为数组（返回 true 或 false）。
isset($arr['key']) 与 array_key_exists('key', $arr)：判断键是否存在；isset 还会判断值不是 null。
类型检查函数：is_int(), is_string(), is_bool(), is_float() 等。
组合检查：通常把 is_array() 与键存在性和类型检查结合使用，来判断某个元素是否“符合预期结构”。
<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">isArraySimple</span></span><span>(</span><span><span class="hljs-params"><span class="hljs-variable">$var</span></span></span><span>): </span><span><span class="hljs-title">bool</span></span><span> {
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$var</span></span><span>);
}
</span><span><span class="hljs-variable">$a</span></span><span> = [</span><span><span class="hljs-number">1</span></span><span>, </span><span><span class="hljs-number">2</span></span><span>, </span><span><span class="hljs-number">3</span></span><span>];
</span><span><span class="hljs-variable">$b</span></span><span> = </span><span><span class="hljs-string">"not an array"</span></span><span>;
</span><span><span class="hljs-title function_ invoke__">var_dump</span></span><span>(</span><span><span class="hljs-title function_ invoke__">isArraySimple</span></span><span>(</span><span><span class="hljs-variable">$a</span></span><span>)); </span><span><span class="hljs-comment">// true</span></span><span>
</span><span><span class="hljs-title function_ invoke__">var_dump</span></span><span>(</span><span><span class="hljs-title function_ invoke__">isArraySimple</span></span><span>(</span><span><span class="hljs-variable">$b</span></span><span>)); </span><span><span class="hljs-comment">// false</span></span><span>
</span></span>说明：这是最基础的一步，任何更复杂的结构验证都应在 is_array() 为 true 的前提下进行。
场景：期望接收到一个用户信息数组，结构如下：
<span><span>[
'id' => int,
'name' => string,
'email' => string,
'meta' => array (可选，若存在则应为数组)
]
</span></span>实现示例：
<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">validateUser</span></span><span>(</span><span><span class="hljs-params"><span class="hljs-keyword">array</span></span></span><span> </span><span><span class="hljs-variable">$arr</span></span><span>): </span><span><span class="hljs-title">bool</span></span><span> {
</span><span><span class="hljs-comment">// 必需字段</span></span><span>
</span><span><span class="hljs-variable">$required</span></span><span> = [</span><span><span class="hljs-string">'id'</span></span><span>, </span><span><span class="hljs-string">'name'</span></span><span>, </span><span><span class="hljs-string">'email'</span></span><span>];
</span><span><span class="hljs-comment">// 先判断确实是数组</span></span><span>
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$arr</span></span><span>)) {
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
}
</span><span><span class="hljs-comment">// 检查必需字段存在</span></span><span>
</span><span><span class="hljs-keyword">foreach</span></span><span> (</span><span><span class="hljs-variable">$required</span></span><span> </span><span><span class="hljs-keyword">as</span></span><span> </span><span><span class="hljs-variable">$key</span></span><span>) {
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">array_key_exists</span></span><span>(</span><span><span class="hljs-variable">$key</span></span><span>, </span><span><span class="hljs-variable">$arr</span></span><span>)) {
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
}
}
</span><span><span class="hljs-comment">// 类型检查</span></span><span>
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">is_int</span></span><span>(</span><span><span class="hljs-variable">$arr</span></span><span>[</span><span><span class="hljs-string">'id'</span></span><span>]) || !</span><span><span class="hljs-title function_ invoke__">is_string</span></span><span>(</span><span><span class="hljs-variable">$arr</span></span><span>[</span><span><span class="hljs-string">'name'</span></span><span>]) || !</span><span><span class="hljs-title function_ invoke__">is_string</span></span><span>(</span><span><span class="hljs-variable">$arr</span></span><span>[</span><span><span class="hljs-string">'email'</span></span><span>])) {
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
}
</span><span><span class="hljs-comment">// 可选字段 meta，如果存在，必须为数组</span></span><span>
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-title function_ invoke__">array_key_exists</span></span><span>(</span><span><span class="hljs-string">'meta'</span></span><span>, </span><span><span class="hljs-variable">$arr</span></span><span>) && !</span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$arr</span></span><span>[</span><span><span class="hljs-string">'meta'</span></span><span>])) {
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
}
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">true</span></span><span>;
}
</span><span><span class="hljs-comment">// 使用示例</span></span><span>
</span><span><span class="hljs-variable">$ok</span></span><span> = [</span><span><span class="hljs-string">'id'</span></span><span> => </span><span><span class="hljs-number">1</span></span><span>, </span><span><span class="hljs-string">'name'</span></span><span> => </span><span><span class="hljs-string">'Alice'</span></span><span>, </span><span><span class="hljs-string">'email'</span></span><span> => </span><span><span class="hljs-string">'[email protected]'</span></span><span>, </span><span><span class="hljs-string">'meta'</span></span><span> => [</span><span><span class="hljs-string">'age'</span></span><span> => </span><span><span class="hljs-number">25</span></span><span>]];
</span><span><span class="hljs-variable">$bad</span></span><span> = [</span><span><span class="hljs-string">'id'</span></span><span> => </span><span><span class="hljs-string">'1'</span></span><span>, </span><span><span class="hljs-string">'name'</span></span><span> => </span><span><span class="hljs-string">'Bob'</span></span><span>, </span><span><span class="hljs-string">'email'</span></span><span> => </span><span><span class="hljs-string">'[email protected]'</span></span><span>];
</span><span><span class="hljs-title function_ invoke__">var_dump</span></span><span>(</span><span><span class="hljs-title function_ invoke__">validateUser</span></span><span>(</span><span><span class="hljs-variable">$ok</span></span><span>)); </span><span><span class="hljs-comment">// true</span></span><span>
</span><span><span class="hljs-title function_ invoke__">var_dump</span></span><span>(</span><span><span class="hljs-title function_ invoke__">validateUser</span></span><span>(</span><span><span class="hljs-variable">$bad</span></span><span>)); </span><span><span class="hljs-comment">// false (id 不是 int)</span></span><span>
</span></span>场景：接收到的数组是一个用户对象的列表（数组的每个元素都应符合 validateUser 上述规则）。
示例代码：
<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">validateUserList</span></span><span>(</span><span><span class="hljs-params"><span class="hljs-variable">$list</span></span></span><span>): </span><span><span class="hljs-title">bool</span></span><span> {
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$list</span></span><span>)) </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
</span><span><span class="hljs-keyword">foreach</span></span><span> (</span><span><span class="hljs-variable">$list</span></span><span> </span><span><span class="hljs-keyword">as</span></span><span> </span><span><span class="hljs-variable">$index</span></span><span> => </span><span><span class="hljs-variable">$item</span></span><span>) {
</span><span><span class="hljs-comment">// 每个元素必须是数组，且结构有效</span></span><span>
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$item</span></span><span>) || !</span><span><span class="hljs-title function_ invoke__">validateUser</span></span><span>(</span><span><span class="hljs-variable">$item</span></span><span>)) {
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
}
}
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">true</span></span><span>;
}
</span></span>说明：此处对每一项先 is_array()，再调用具体的验证函数。对外来数据（例如 API 请求体）进行防卫性检查非常重要。
当数组具有未知深度或多层嵌套时，常用递归函数来验证结构。例如：树状菜单或多级分类结构。
递归示例（每个节点应包含 id 和 children（数组或空））：
<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">validateTreeNode</span></span><span>(</span><span><span class="hljs-params"><span class="hljs-variable">$node</span></span></span><span>): </span><span><span class="hljs-title">bool</span></span><span> {
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$node</span></span><span>)) </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
</span><span><span class="hljs-comment">// 必须含 id</span></span><span>
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">array_key_exists</span></span><span>(</span><span><span class="hljs-string">'id'</span></span><span>, </span><span><span class="hljs-variable">$node</span></span><span>) || !</span><span><span class="hljs-title function_ invoke__">is_int</span></span><span>(</span><span><span class="hljs-variable">$node</span></span><span>[</span><span><span class="hljs-string">'id'</span></span><span>])) {
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
}
</span><span><span class="hljs-comment">// children 可选，但若存在必须为数组，每个子元素必须也是合法节点</span></span><span>
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-title function_ invoke__">array_key_exists</span></span><span>(</span><span><span class="hljs-string">'children'</span></span><span>, </span><span><span class="hljs-variable">$node</span></span><span>)) {
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$node</span></span><span>[</span><span><span class="hljs-string">'children'</span></span><span>])) </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
</span><span><span class="hljs-keyword">foreach</span></span><span> (</span><span><span class="hljs-variable">$node</span></span><span>[</span><span><span class="hljs-string">'children'</span></span><span>] </span><span><span class="hljs-keyword">as</span></span><span> </span><span><span class="hljs-variable">$child</span></span><span>) {
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">validateTreeNode</span></span><span>(</span><span><span class="hljs-variable">$child</span></span><span>)) </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
}
}
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">true</span></span><span>;
}
</span></span>可以将“期望的结构”抽象为规则数组，让验证器更通用、可复用。
规则格式示例（伪规则）：
<span><span><span class="hljs-variable">$schema</span></span><span> = [
</span><span><span class="hljs-string">'id'</span></span><span> => </span><span><span class="hljs-string">'int'</span></span><span>,
</span><span><span class="hljs-string">'name'</span></span><span> => </span><span><span class="hljs-string">'string'</span></span><span>,
</span><span><span class="hljs-string">'email'</span></span><span> => </span><span><span class="hljs-string">'string'</span></span><span>,
</span><span><span class="hljs-string">'meta'</span></span><span> => [</span><span><span class="hljs-string">'type'</span></span><span> => </span><span><span class="hljs-string">'array'</span></span><span>, </span><span><span class="hljs-string">'schema'</span></span><span> => [</span><span><span class="hljs-string">'age'</span></span><span> => </span><span><span class="hljs-string">'int'</span></span><span>]]
];
</span></span>通用验证器（简单实现）：
<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">validateBySchema</span></span><span>(</span><span><span class="hljs-params"><span class="hljs-variable">$data</span></span></span><span>, </span><span><span class="hljs-variable">$schema</span></span><span>): </span><span><span class="hljs-title">bool</span></span><span> {
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$data</span></span><span>) || !</span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$schema</span></span><span>)) </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
</span><span><span class="hljs-keyword">foreach</span></span><span> (</span><span><span class="hljs-variable">$schema</span></span><span> </span><span><span class="hljs-keyword">as</span></span><span> </span><span><span class="hljs-variable">$key</span></span><span> => </span><span><span class="hljs-variable">$rule</span></span><span>) {
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">array_key_exists</span></span><span>(</span><span><span class="hljs-variable">$key</span></span><span>, </span><span><span class="hljs-variable">$data</span></span><span>)) {
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>; </span><span><span class="hljs-comment">// 可扩展为可选字段支持</span></span><span>
}
</span><span><span class="hljs-variable">$value</span></span><span> = </span><span><span class="hljs-variable">$data</span></span><span>[</span><span><span class="hljs-variable">$key</span></span><span>];
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-title function_ invoke__">is_string</span></span><span>(</span><span><span class="hljs-variable">$rule</span></span><span>)) {
</span><span><span class="hljs-comment">// 简单类型匹配</span></span><span>
</span><span><span class="hljs-variable">$typeCheck</span></span><span> = </span><span><span class="hljs-keyword">match</span></span><span> (</span><span><span class="hljs-variable">$rule</span></span><span>) {
</span><span><span class="hljs-string">'int'</span></span><span> => </span><span><span class="hljs-title function_ invoke__">is_int</span></span><span>(</span><span><span class="hljs-variable">$value</span></span><span>),
</span><span><span class="hljs-string">'string'</span></span><span> => </span><span><span class="hljs-title function_ invoke__">is_string</span></span><span>(</span><span><span class="hljs-variable">$value</span></span><span>),
</span><span><span class="hljs-string">'bool'</span></span><span> => </span><span><span class="hljs-title function_ invoke__">is_bool</span></span><span>(</span><span><span class="hljs-variable">$value</span></span><span>),
</span><span><span class="hljs-string">'float'</span></span><span> => </span><span><span class="hljs-title function_ invoke__">is_float</span></span><span>(</span><span><span class="hljs-variable">$value</span></span><span>),
</span><span><span class="hljs-string">'array'</span></span><span> => </span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$value</span></span><span>),
</span><span><span class="hljs-keyword">default</span></span><span> => </span><span><span class="hljs-literal">false</span></span><span>
};
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-variable">$typeCheck</span></span><span>) </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
} </span><span><span class="hljs-keyword">elseif</span></span><span> (</span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$rule</span></span><span>) && </span><span><span class="hljs-keyword">isset</span></span><span>(</span><span><span class="hljs-variable">$rule</span></span><span>[</span><span><span class="hljs-string">'type'</span></span><span>]) && </span><span><span class="hljs-variable">$rule</span></span><span>[</span><span><span class="hljs-string">'type'</span></span><span>] === </span><span><span class="hljs-string">'array'</span></span><span>) {
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$value</span></span><span>)) </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-keyword">isset</span></span><span>(</span><span><span class="hljs-variable">$rule</span></span><span>[</span><span><span class="hljs-string">'schema'</span></span><span>])) {
</span><span><span class="hljs-comment">// 对数组内部采用相同的 schema 进行验证（假设是关联数组）</span></span><span>
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">validateBySchema</span></span><span>(</span><span><span class="hljs-variable">$value</span></span><span>, </span><span><span class="hljs-variable">$rule</span></span><span>[</span><span><span class="hljs-string">'schema'</span></span><span>])) </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>;
}
} </span><span><span class="hljs-keyword">else</span></span><span> {
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">false</span></span><span>; </span><span><span class="hljs-comment">// 未知规则</span></span><span>
}
}
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-literal">true</span></span><span>;
}
</span></span>提示：真实项目中应使用成熟的验证库（如使用框架自带验证器或第三方库）来代替自写实现，但理解原理有助于调试和定制。
区分 isset 和 array_key_exists：当数组键存在但值为 null 时，isset 返回 false，而 array_key_exists 返回 true。如果 null 是允许值，请使用 array_key_exists。
外部输入的数据类型不可靠：JSON 解码（json_decode）会把数字转为 int/float，但从表单提交来的都是字符串，应使用类型转换或严格检查。
不要只用 is_array 就完事：is_array 只是第一步，通常还需要键存在性、类型、取值范围等检查。
注意空数组与非数组的区别：[] 是数组，null / '' / 0 不是数组。对空数组是否允许要在逻辑上先定义清楚。
性能考虑：大量数据的逐项递归验证可能有性能开销，必要时可限制最大深度或批量校验策略。
假设 API 接收 POST /users/batch， body 为 JSON 数组，每个元素应为用户对象（参见第 3 节）。示例处理流程：
<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-comment">// 1. 获取原始 body</span></span><span>
</span><span><span class="hljs-variable">$raw</span></span><span> = </span><span><span class="hljs-title function_ invoke__">file_get_contents</span></span><span>(</span><span><span class="hljs-string">'php://input'</span></span><span>);
</span><span><span class="hljs-variable">$data</span></span><span> = </span><span><span class="hljs-title function_ invoke__">json_decode</span></span><span>(</span><span><span class="hljs-variable">$raw</span></span><span>, </span><span><span class="hljs-literal">true</span></span><span>); </span><span><span class="hljs-comment">// 第二个参数 true 返回关联数组</span></span><span>
</span><span><span class="hljs-comment">// 2. 基础检查</span></span><span>
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-title function_ invoke__">is_array</span></span><span>(</span><span><span class="hljs-variable">$data</span></span><span>)) {
</span><span><span class="hljs-title function_ invoke__">http_response_code</span></span><span>(</span><span><span class="hljs-number">400</span></span><span>);
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-title function_ invoke__">json_encode</span></span><span>([</span><span><span class="hljs-string">'error'</span></span><span> => </span><span><span class="hljs-string">'请求体必须为 JSON 数组'</span></span><span>]);
</span><span><span class="hljs-keyword">exit</span></span><span>;
}
</span><span><span class="hljs-comment">// 3. 验证每项</span></span><span>
</span><span><span class="hljs-variable">$valid</span></span><span> = </span><span><span class="hljs-title function_ invoke__">validateUserList</span></span><span>(</span><span><span class="hljs-variable">$data</span></span><span>);
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-variable">$valid</span></span><span>) {
</span><span><span class="hljs-title function_ invoke__">http_response_code</span></span><span>(</span><span><span class="hljs-number">422</span></span><span>);
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-title function_ invoke__">json_encode</span></span><span>([</span><span><span class="hljs-string">'error'</span></span><span> => </span><span><span class="hljs-string">'数组中存在不符合结构的元素'</span></span><span>]);
</span><span><span class="hljs-keyword">exit</span></span><span>;
}
</span><span><span class="hljs-comment">// 4. 后续处理（写库、返回成功等）</span></span><span>
</span><span><span class="hljs-title function_ invoke__">http_response_code</span></span><span>(</span><span><span class="hljs-number">200</span></span><span>);
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-title function_ invoke__">json_encode</span></span><span>([</span><span><span class="hljs-string">'status'</span></span><span> => </span><span><span class="hljs-string">'ok'</span></span><span>]);
</span></span>filter_var()：验证 email、URL 等（例如 FILTER_VALIDATE_EMAIL）。
ctype_digit()：判断字符串是否只包含数字（当需要字符串形式的数字时）。
PHP 8 的 match、类型声明（type hints）和联合类型可以在函数签名上提供额外保证。
使用单元测试（PHPUnit）为验证器写测试用例，覆盖各种边界情形。
is_array() 很重要，但只是数组结构验证的第一步。要判断“结构是否符合预期”，需要：键的存在性、值的类型、可选字段规则、嵌套结构验证以及取值范围验证。
把验证逻辑封装成小函数或基于 schema 的通用验证器，能提高可维护性与可复用性。
对外部输入要始终保持防御性（防止类型错乱、缺失字段、额外字段或恶意数据）。
在复杂场景下，优先考虑使用成熟的验证库或框架提供的验证功能，并通过单元测试来保证验证规则的正确性。
