Php grabs a word of the string, does not replace it, and adds <br>

assume that the string is 

abc@gmail.com
    Can
  1. realize the name of the string before catching @? (abc) no matter how long.
    2. Can
  2. automatically add a
    before each string @? It will not replace any Kansi. 
abc
@gmail.com
Php php7 string
Mar.01,2021
$abc = "12ww@qq.com";
$a = strpos ($abc, "@");
$str = substr ($abc,0,$a). "
" .substr ($abc,$a); 

$email = 'abc@gmail.com';
$email = str_replace("@","<br>@",$email);

$email = 'abc@gmail.com';
$arr = explode ("@", $email);
echo $arr [0], "
",' @'. $arr

Previous: How to set Referer in axios of vue

Next: There are three ul, on my page. I switch the contents of the ul when I click, but when I switch, I will see the content of the previous ul flash. How to solve the problem of flashing?

css mysql arrays josn react html typescript webpack npm sass R objective-c .net sql-server jquery python-3.x angularjs django angular excel regex iphone ajax linux xml pandas vba spring database wordpress string wpf xcode windows bash postgresql oracle multithreading eclipse list firebase algorithm macos forms image scala visual-studio azure bootstrap spring-boot react-native python-2.7 docker performance function winforms matlab powershell apache dataframe api sqlite numpy rest shell selenium flutter dart maven loops qt swing android-studio csv express file class tensorflow sorting codeigniter perl
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1e8e45c-11bf.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e8e45c-11bf.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
Need Help?