PHP中正确操作对象数组：实例化与元素添加指南

<?php
class DNA {
    private $RSID;
    private $CHROMOSOME;

    public function setRSID($RSID) { $this->RSID = $RSID; }
    public function setCHROMOSOME($CHROMOSOME) { $this->CHROMOSOME = $CHROMOSOME; }
    public function getRSID() { return $this->RSID; }
    public function getCHROMOSOME() { return $this->CHROMOSOME; }
}

$dna1[] = new DNA; // 此时只创建了一个DNA对象，并赋给了$dna1[0]

// 尝试对不存在的对象实例进行属性设置，这将导致错误或意外行为
$dna1[0]->setRSID(1);
$dna1[0]->setCHROMOSOME(2);

$dna1[1]->setRSID(5); // 错误：$dna1[1]尚未被赋值为对象，尝试在非对象上调用方法
$dna1[1]->setCHROMOSOME(3);

$dna1[2]->setRSID(7); // 错误：$dna1[2]尚未被赋值为对象，尝试在非对象上调用方法
$dna1[2]->setCHROMOSOME(0);
?>

<?php
class DNA {
    private $RSID;
    private $CHROMOSOME;

    public function setRSID($RSID) { $this->RSID = $RSID; return $this; } // 链式调用支持
    public function setCHROMOSOME($CHROMOSOME) { $this->CHROMOSOME = $CHROMOSOME; return $this; } // 链式调用支持
    public function getRSID() { return $this->RSID; }
    public function getCHROMOSOME() { return $this->CHROMOSOME; }
}

// 1. 初始化一个空数组
$dna1 = [];

// 2. 为每个数组位置独立创建并赋值对象实例
$dna1[0] = new DNA; // 创建第一个DNA对象
$dna1[0]->setRSID(1);
$dna1[0]->setCHROMOSOME(2);

$dna1[1] = new DNA; // 创建第二个DNA对象
$dna1[1]->setRSID(5);
$dna1[1]->setCHROMOSOME(3);

$dna1[2] = new DNA; // 创建第三个DNA对象
$dna1[2]->setRSID(7);
$dna1[2]->setCHROMOSOME(0);

// 验证结果
echo "DNA 1 RSID: " . $dna1[0]->getRSID() . ", CHROMOSOME: " . $dna1[0]->getCHROMOSOME() . PHP_EOL;
echo "DNA 2 RSID: " . $dna1[1]->getRSID() . ", CHROMOSOME: " . $dna1[1]->getCHROMOSOME() . PHP_EOL;
echo "DNA 3 RSID: " . $dna1[2]->getRSID() . ", CHROMOSOME: " . $dna1[2]->getCHROMOSOME() . PHP_EOL;
?>

<?php
class DNA {
    private $RSID;
    private $CHROMOSOME;

    public function setRSID($RSID) { $this->RSID = $RSID; return $this; }
    public function setCHROMOSOME($CHROMOSOME) { $this->CHROMOSOME = $CHROMOSOME; return $this; }
    public function getRSID() { return $this->RSID; }
    public function getCHROMOSOME() { return $this->CHROMOSOME; }
}

$dna_objects = [];

// 添加第一个对象
$obj1 = new DNA;
$obj1->setRSID(1);
$obj1->setCHROMOSOME(2);
$dna_objects[] = $obj1; // 自动添加到下一个可用索引

// 添加第二个对象
$obj2 = new DNA;
$obj2->setRSID(5);
$obj2->setCHROMOSOME(3);
$dna_objects[] = $obj2;

// 添加第三个对象
$obj3 = new DNA;
$obj3->setRSID(7);
$obj3->setCHROMOSOME(0);
$dna_objects[] = $obj3;

// 也可以直接在赋值时实例化（PHP 7+ 支持链式调用）
$dna_objects[] = (new DNA())->setRSID(10)->setCHROMOSOME(4);

// 验证
foreach ($dna_objects as $index => $dna) {
    echo "DNA " . ($index + 1) . " RSID: " . $dna->getRSID() . ", CHROMOSOME: " . $dna->getCHROMOSOME() . PHP_EOL;
}
?>

<?php
class DNA {
    private $RSID;
    private $CHROMOSOME;

    public function __construct($RSID = null, $CHROMOSOME = null) { // 添加构造函数简化初始化
        if ($RSID !== null) $this->RSID = $RSID;
        if ($CHROMOSOME !== null) $this->CHROMOSOME = $CHROMOSOME;
    }
    public function setRSID($RSID) { $this->RSID = $RSID; return $this; }
    public function setCHROMOSOME($CHROMOSOME) { $this->CHROMOSOME = $CHROMOSOME; return $this; }
    public function getRSID() { return $this->RSID; }
    public function getCHROMOSOME() { return $this->CHROMOSOME; }
}

$dna_data = [
    ['RSID' => 1, 'CHROMOSOME' => 2],
    ['RSID' => 5, 'CHROMOSOME' => 3],
    ['RSID' => 7, 'CHROMOSOME' => 0],
    ['RSID' => 10, 'CHROMOSOME' => 4],
];

$dna_collection = [];
foreach ($dna_data as $data) {
    // 使用构造函数初始化对象更简洁
    $dna_instance = new DNA($data['RSID'], $data['CHROMOSOME']);
    $dna_collection[] = $dna_instance; // 动态添加
}

// 验证
foreach ($dna_collection as $index => $dna) {
    echo "Collection DNA " . ($index + 1) . " RSID: " . $dna->getRSID() . ", CHROMOSOME: " . $dna->getCHROMOSOME() . PHP_EOL;
}
?>