要使用PHP的array_filter實現(xiàn)高級條件過濾，需結(jié)合自定義邏輯和閉包。 1. 基本用法中array_filter通過回調(diào)函數(shù)保留返回true的元素。 2. 對關(guān)聯(lián)數(shù)組可使用if語句組合多個條件，如同時檢查用戶活躍狀態(tài)、年齡和角色。 3. 利用use關(guān)鍵字引入外部變量（如$minAge、$allowedRoles）實現(xiàn)動態(tài)過濾條件。 4. 將過濾邏輯拆分為獨立函數(shù)（如isActive、isAdult、hasValidRole）以提高可讀性和復(fù)用性。 5. 處理邊緣情況時需顯式檢查null、缺失鍵或空值，避免鬆散比較導(dǎo)致的錯誤。 6. 在復(fù)雜場景下可通過回調(diào)分發(fā)機制，根據(jù)類型動態(tài)組合多個過濾器。最終應(yīng)確?；卣{(diào)內(nèi)數(shù)據(jù)驗證完整、無副作用，並在處理大數(shù)據(jù)時注意性能優(yōu)化，從而構(gòu)建清晰且可擴展的過濾邏輯。

When working with arrays in PHP, filtering data based on complex or advanced conditions is a common requirement. While array_filter is a powerful built-in function, its real potential shines when combined with custom logic — including if statements and nested conditions — to handle more sophisticated filtering scenarios.

Here's how to use array_filter effectively with advanced conditional patterns.

1. Basic array_filter Recap

By default, array_filter loops over each element in an array and keeps only those for which the callback returns true .

 $numbers = [1, 2, 3, 4, 5, 6];
$even = array_filter($numbers, function($n) {
    return $n % 2 === 0;
});
// Result: [2, 4, 6]

But real-world data is rarely this simple.

2. Filtering Associative Arrays with Multiple Conditions

Suppose you have an array of users and want to filter based on multiple criteria like age, role, and activity status.

 $users = [
    ['name' => 'Alice', 'age' => 25, 'role' => 'admin', 'active' => true],
    ['name' => 'Bob', 'age' => 17, 'role' => 'user', 'active' => false],
    ['name' => 'Charlie', 'age' => 30, 'role' => 'moderator', 'active' => true],
    ['name' => 'Diana', 'age' => 19, 'role' => 'user', 'active' => true],
];

Now, filter for:

• Active users
• Age 18 or older
• Role is either 'user' or 'admin'

 $filtered = array_filter($users, function($user) {
    if (!$user['active']) {
        return false;
    }
    if ($user[&#39;age&#39;] < 18) {
        return false;
    }
    if (!in_array($user[&#39;role&#39;], [&#39;user&#39;, &#39;admin&#39;])) {
        return false;
    }
    return true;
});

This approach allows full control using if logic, making it easy to debug and extend.

3. Using External Variables in Filters with use

Sometimes your conditions depend on dynamic values (eg, minimum age from input).

 $minAge = 21;
$allowedRoles = ['user', 'admin'];

$filtered = array_filter($users, function($user) use ($minAge, $allowedRoles) {
    return $user['active'] &&
           $user['age'] >= $minAge &&
           in_array($user['role'], $allowedRoles);
});

The use keyword imports variables into the closure's scope — essential for dynamic filtering.

4. Combining Multiple Filter Rules (Reusable Logic)

For better maintainability, break logic into smaller functions.

 function isActive($user) {
    return $user['active'];
}

function isAdult($user, $minAge = 18) {
    return $user['age'] >= $minAge;
}

function hasValidRole($user, $roles) {
    return in_array($user['role'], $roles);
}

// Now compose them
$filtered = array_filter($users, function($user) {
    return isActive($user) &&
           isAdult($user, 18) &&
           hasValidRole($user, ['user', 'admin']);
});

This improves readability and reusability across different filters.

5. Filtering with Negation and Edge Cases

Be careful with null , empty strings, or missing keys.

 $products = [
    ['name' => 'Laptop', 'price' => 1200, 'stock' => 5],
    ['name' => 'Mouse', 'price' => null, 'stock' => 0],
    ['name' => 'Keyboard', 'price' => 80, 'stock' => 3],
];

// Only in-stock items with valid price
$available = array_filter($products, function($product) {
    if (!isset($product['price']) || $product['price'] === null) {
        return false;
    }
    if (!isset($product[&#39;stock&#39;]) || $product[&#39;stock&#39;] <= 0) {
        return false;
    }
    return true;
});

Explicit checks prevent bugs caused by loose comparison.

6. Filtering with Callback Dispatch (Advanced Pattern)

For highly dynamic systems, route to different filters based on type.

 $filters = [
    'admin' => function($user) { return $user['role'] === 'admin'; },
    'active_adults' => function($user) { return $user['active'] && $user['age'] >= 18; },
    'min_age' => function($user) use ($minAge) { return $user['age'] >= $minAge; }
];

// Apply multiple filters dynamically
$activeAdmins = array_filter($users, function($user) use ($filters) {
    return $filters['admin']($user) && $filters['active_adults']($user);
});

This pattern works well in search or API filtering layers.

Final Notes

• Always validate data inside the callback (check for missing keys, types).
• Use use to inject dependencies cleanly.
• Avoid side effects — array_filter should not modify external state.
• Consider performance: complex logic on large arrays may need optimization or early returns.

With smart use of if logic and closures, array_filter becomes a flexible tool for handling real-world data filtering needs.

Basically, it's not just about simple checks — it's about structuring your conditions clearly and scalably.

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