为什么输入Y和Z的差别这吗大,是什么原因
$str = '';
$str_ = '';
$arr = ['A','B','C','D','E','F','G','H','I','J','K','L','M',
'N','O','P','Q','R','S','T','U','V','W','X','Y','Z',];
foreach ($arr as $v) {
$str .= $v.',';
foreach ($arr as $vv) {
$str_ .= $v.$vv.',';
}
$str_ .= '<br>';
}
echo $str.'<br>';
echo $str_;
for ($i = 0; $i <= 1000; $i++) {
}