implode: the value of the one-dimensional array is connected to a string

<?php

 

$arr = ['C','D','E'];

echo 'original array has', count ($ arr), 'members';

echo 'They are:', implode ( ',', $ arr);

$length = array_unshift($arr,'A','B');

echo 'conventional', $ length, 'member';

echo 'They are:', implode ( ',', $ arr);

$arr = ['id' => 1, 'unsername' => 'tom'];

array_unshift($arr,22,true);

print_r($arr);

$arr = ['C','D','E'];

array_push($arr,'F','G');

print_r($arr);

$arr = ['C','D','E'];

$value = array_shift($arr);

echo $value;

print_r($arr);