PHP verifies whether the username starts with a letter and verifies the password_PHP tutorial

Verify whether the username starts with a letter and verify that the password can only be a combination of numbers and letters
Three commonly used verification functions Verify email address format Verify password can only be a combination of numbers and letters Verify whether the username starts with a letter code, this is used when users register or submit forms.

function is_email($email)
 {
  if (preg_match("/[a-za-z0-9]+@[a-za-z0-9]+.[a-z]{2,4}/",$email,$mail))
  {
      return true;
  }
  else
  {
      return false;
  }
 } /**
  * 验证用户名是否以字母开头
  */


function is_user_name($user)
 {
  if (preg_match("/^[a-za-z]{1}([a-za-z0-9]|[._]){3,19}$/",$user,$username))
  {
      return true;
  }
  else
  {
      return false;
  }
 } /**
  * 验证密码只能为数字和字母的组合
  */


function is_ps教程d($psd)
 {
  if (preg_match("/^(w){4,20}$/",$psd,$password))
  {
      return true;
  }
  else
  {
      return false;
  }
 }

http://www.bkjia.com/PHPjc/447003.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/447003.htmlTechArticleVerify whether the username starts with a letter and verify that the password can only be a combination of numbers and letters. Three commonly used codes The verification function verifies the email address format and the verification password can only be numbers and letters...