Php 如何将数字组合成一组

下面的代码根据起始字符将字符串分成若干组。我现在尝试将所有数字合并到一个组中，而不是每个起始数字都有自己的组。有人能帮我吗，因为我不知道如何修改以实现这一点

$last = '';
foreach($brandsArray as $words){
    $current = substr($words, 0, 1);
    if(strtoupper($current) != strtoupper($last)) {
         echo "\n
         <a name=\"". strtoupper($current) ."\"><li class=\"title\">" . strtoupper($current) . "</li></a>\n\n";
    }
    echo '<li>'. $words . "</li>\n";
    $last = $current;
}

我希望输出是什么样子的

**#**
1
121
57 
876

**A**
Apple
Apple1

**B**
Banana
Banana123

**D**
Delta

它目前正在做的事情如下

**1**
1
121

**5**
57 

**8**
876

**A**
Apple
Apple1

**B**
Banana
Banana123

**D**
Delta

---

对于上述问题中给定的输入和预期输出

$brandsArray = array('1', '121', '57', '876', 'Apple', 'Apple1', 'Banana', 'Banana123', 'Delta');
$last = '';
foreach($brandsArray as $words){
    // setting the current value as # if is number
    $current = is_numeric($words)?"#":substr($words, 0, 1);
    if (strtoupper($current) != strtoupper($last)) {
         echo "\n
         <a name=\"". strtoupper($current) ."\"><li class=\"title\">" . strtoupper($current) . "</li></a>\n\n";
    }
    echo '<li>'. $words . "</li>\n";
    $last = $current;
}

---

请提供输入和预期输出的示例。strothigh$words\n\n@VeshrajJoshi-更新以显示输入、它在做什么以及我希望它做什么

$brandsArray = array('1', '121', '57', '876', 'Apple', 'Apple1', 'Banana', 'Banana123', 'Delta');
$last = '';
foreach($brandsArray as $words){
    // setting the current value as # if is number
    $current = is_numeric($words)?"#":substr($words, 0, 1);
    if (strtoupper($current) != strtoupper($last)) {
         echo "\n
         <a name=\"". strtoupper($current) ."\"><li class=\"title\">" . strtoupper($current) . "</li></a>\n\n";
    }
    echo '<li>'. $words . "</li>\n";
    $last = $current;
}