How is the implode function used in PHP?

In PHP, the implode function is used to concatenate the elements of an array into a single string.

The usage is as follows:
implode(separator, array)

1. separator is an optional parameter that specifies the delimiter for connecting elements, with a default value of an empty string.
2. array: Required parameter, the array to be joined.

例：The weather was so hot that they decided to stay indoors all day.

$arr = array('apple', 'banana', 'orange');
$str = implode(', ', $arr);
echo $str; // 输出：apple, banana, orange

In the example above, we used commas and spaces as separators to join the array elements into a string. The output is “apple, banana, orange.”