常用的正则表达式

 

^从行开始处匹配，$从行结束处开始匹配。
\A从字符串开始处匹配，\Z从字符串结束处匹配。

 

1.匹配十六进制的字符串

http://stackoverflow.com/questions/223832/check-a-string-to-see-if-all-characters-are-hexadecimal-values

// For C-style hex notation (0xFF) you can use @"\A\b(0[xX])?[0-9a-fA-F]+\b\Z"

@"\A\b[0-9a-fA-F]+\b\Z"

@"^[0-9a-fA-F]$"

关于\A和\b的，还要抽时间做实验

 

正则邮箱regex for email

How to validate an email address in JavaScript

Using regular expressions is probably the best way. You can see a bunch of tests here (taken from chromium)

function validateEmail(email) {
    const re = /^(([^<>()[\]\\.,;:\s@"]+(\.[^<>()[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
    return re.test(String(email).toLowerCase());
}

Here's the example of regular expresion that accepts unicode:

const re = /^(([^<>()[\]\.,;:\s@\"]+(\.[^<>()[\]\.,;:\s@\"]+)*)|(\".+\"))@(([^<>()[\]\.,;:\s@\"]+\.)+[^<>()[\]\.,;:\s@\"]{2,})$/i;

But keep in mind that one should not rely only upon JavaScript validation. JavaScript can easily be disabled. This should be validated on the server side as well.

Here's an example of the above in action:

function validateEmail(email) {
  const re = /^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
  return re.test(email);
}

function validate() {
  const $result = $("#result");
  const email = $("#email").val();
  $result.text("");

  if (validateEmail(email)) {
    $result.text(email + " is valid :)");
    $result.css("color", "green");
  } else {
    $result.text(email + " is not valid :(");
    $result.css("color", "red");
  }
  return false;
}

$("#email").on("input", validate);

 

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<label for=email>Enter an email address:</label>
<input id="email">
<h2 id="result"></h2>

 

另外一个答案，枚举了很多正则

How to write Particular Regular Expression in android or java.

1) USER_NAME = "^[A-Za-z0-9_-]{min number of character,max number of character}$";

2) TELEPHONE = "(^\\+)?[0-9()-]*";

3) TELEPHONE_OPTIONAL = "^($|(^\\+)?[0-9()-]*)$";

4) EMAIL = "[a-zA-Z0-9_\\.\\+-]+@[a-zA-Z0-9-]+\\.[a-zA-Z0-9-\\.]+";

5) EMAIL_OPTIONAL = "^($|[a-zA-Z0-9_\\.\\+-]+@[a-zA-Z0-9-]+\\.[a-zA-Z0-9-\\.]+)$";

6) WEB_URL = "^($|(http:\\/\\/|https:\\/\\/)?(www.)?([a-zA-Z0-9]+).[a-zA-Z0-9]*.[a-z]{3}.?([a-z]+)?)$";

7) WEB_URL_YOUTUBE_BE = "https?\\:\\/\\/(www\\.)?youtu(\\.)?be(\\.com)?\\/.*(\\?v=|\\/v\\/)?[a-zA-Z0-9_\\-]+";

8) POSTAL_ADDRESS = "[a-zA-Z\\d\\s\\-\\,\\#\\.\\+]+";

9) FIELD_NOT_EMPTY = "[^\\s]*";

10) PINCODE = "^([0-9]{6})?$";

11) IFSC_CODE = "^[^\\s]{4}\\d{7}$";

12) SWIFT_CODE = "^([0-9]{10})?$";

13) PINCODE = "^([0-9]{6})?$";

 

Invalid Characters in Internet Email Addresses

Internet email addresses must include only RFC-compliant characters, which include:

• Numbers 0-9

• Uppercase letters A-Z

• Lowercase letters a-z

• Plus sign +

• Hyphen -

• Underscore _

• Tilde ~