php 二维数组查询

$students = [
    ['id' => 1, 'name' => 'Alice', 'age' => 20],
    ['id' => 2, 'name' => 'Bob', 'age' => 22],
    ['id' => 3, 'name' => 'Charlie', 'age' => 21]
];

function findStudentById($students, $id) {
    foreach ($students as $student) {
        if ($student['id'] == $id) {
            return $student;
        }
    }
    return null; // 如果没有找到，返回null
}

$student = findStudentById($students, 2);
if ($student) {
    echo "Found student: " . $student['name'] . ", Age: " . $student['age'];
} else {
    echo "Student not found.";
}

// 使用关联数组优化查询
$studentsById = [];
foreach ($students as $student) {
    $studentsById[$student['id']] = $student;
}

function findStudentByIdOptimized($studentsById, $id) {
    return isset($studentsById[$id]) ? $studentsById[$id] : null;
}

$student = findStudentByIdOptimized($studentsById, 2);
if ($student) {
    echo "Found student: " . $student['name'] . ", Age: " . $student['age'];
} else {
    echo "Student not found.";
}