无法从用户名中删除空格 [重复]

Question

我正在尝试删除用户名中的空格，但出了点问题。我的另一种情况继续运行。即使我把用户名没有空格，它也不起作用

这是我的代码

$username   = trim($_POST['username']);
  $username     = strip_tags($username);
  $username     = htmlspecialchars($username);

     // username validation
  if (empty($username)) {
   $error = true;
   $usernameError = "Please enter your username.";
  } else if (strlen($username) < 3) {
   $error = true;
   $usernameError = "Username must have at least 3 characters.";
  } else if (preg_match("/^(?=.*[a-z])(?=.*[0-9])[a-z0-9][a-z0-9_]{1,6}[a-z0-9]$/", $username)) {
   $error = true;
   $usernameError = "Username must contain alphabets and numbers.";
  } 

Answer 1

根据你的情况，我建议你使用正则表达式，你可以在你的代码中尝试这个示例来检查它是否正确，希望对你有帮助：

$username = trim('hello 123'); 
$username = strip_tags($username); 
$username = htmlspecialchars($username); 

$usernameError = 'valid';
// username validation 
if (empty($username)) { $error = true; $usernameError = "Please enter your username."; } 
else if (strlen($username) < 3) { 
    $error = true; $usernameError = "Username must have at least 3 characters."; 
} 
else if (preg_match("/\s/", $username)) 
{ 
    $error = true; 
    $usernameError = "Username can't contain whitespace."; 
}
else if (!preg_match("/^[a-z0-9][a-z0-9_]{2,9}$/", $username)) // case maximum 10 characters and only accept "a-z 0-9 and _"
{ 
    $error = true; 
    $usernameError = "Username can only contain alphabet, number and _"; 
}
if (empty($usernameError)) {
    echo 'valid';
}
echo $usernameError;

Answer 2

我可能会建议您在这里只使用一个正则表达式：

^(?=.*[a-z])(?=.*[0-9])[a-z0-9][a-z0-9_]{1,6}[a-z0-9]$

您更新的 PHP 代码：

$username = "hello123";
if (preg_match("/^(?=.*[a-z])(?=.*[0-9])[a-z0-9][a-z0-9_]{1,6}[a-z0-9]$/i", $username)) {
    echo "valid username";
}

Demo

如果您想向选择无效用户名的用户提供反馈，您可以一次简单地说明所有要求，而不是按顺序做事。

下面是正则表达式模式的解释：

^                   from the start of the username
    (?=.*[a-z])     lookahead and assert one letter present
    (?=.*[0-9])     lookahead and assert one number present
    [a-z0-9]        one letter or number
    [a-z0-9_]{1,6}  one letter/number/underscore
    [a-z0-9]        one letter or number (total 3-8)
$                   end of the username