Php 数组，如何显示；“改变价值观”；只有

假设我有一个带有日期和季节的数组，每天有一个条目。我只想在季节值更改时打印数组行

该数组如下所示：

2009-10-28 00:00:00 (good season)  

2009-10-29 00:00:00 (good season) 

2009-10-30 00:00:00 (good season) 

2009-10-31 00:00:00 (good season) 

2009-11-01 00:00:00 (good season) 

2009-11-02 00:00:00 (bad season) 

2009-11-03 00:00:00 (bad season) 

2009-11-04 00:00:00 (bad season) 

2009-11-05 00:00:00 (bad season) 

---

循环浏览，记录上一季：

$lastSeason = '';

foreach ($array as $date => $season)
{
    if ($season != $lastSeason)
        echo "Season changed on " . $date;

    $lastSeason = $season;
}

---

循环浏览，记录上一季：

$lastSeason = '';

foreach ($array as $date => $season)
{
    if ($season != $lastSeason)
        echo "Season changed on " . $date;

    $lastSeason = $season;
}

---

存储上一次迭代的状态，并将其与当前迭代的状态进行比较。如果它们不同，请打印项目：

$last = null;
foreach ($array as $val) {
    if (preg_match('/^\d{4}-\d{2}\d{2} \d{2}:\d{2}:\d{2} \((good|bad) season\)$/', $val, $match)) {
        if ($last != $match[1]) {
            echo $val;
        }
        $last = $match[1];
    }
}

---

存储上一次迭代的状态，并将其与当前迭代的状态进行比较。如果它们不同，请打印项目：

$last = null;
foreach ($array as $val) {
    if (preg_match('/^\d{4}-\d{2}\d{2} \d{2}:\d{2}:\d{2} \((good|bad) season\)$/', $val, $match)) {
        if ($last != $match[1]) {
            echo $val;
        }
        $last = $match[1];
    }
}

---

假设您的数组是数组的数组：

if(count($array) > 0) {
  $prev = $array[0]['season'];

  foreach ($array as $row) {
    if ($row['season'] != $prev) echo $row['date'];

    $prev = $row['season'];
  }
}

---

假设您的数组是数组的数组：

if(count($array) > 0) {
  $prev = $array[0]['season'];

  foreach ($array as $row) {
    if ($row['season'] != $prev) echo $row['date'];

    $prev = $row['season'];
  }
}

---

为什么要用复杂正则表达式来解决这么简单的问题？为什么要用复杂正则表达式来解决这么简单的问题？