Examples of the most commonly used regular expressions

Regular expressions are a seemingly simple tool that is important in a variety of programming languages. This article describes several of the most commonly used regular expression examples, which can be applied directly to your project as an example, or as a small example to learn and understand.

Match Chinese characters

[\u4e00-\u9fa5]

Commentary: Matching Chinese is really a headache, with this expression will be easy to do

Match Double-byte characters (including Chinese characters)

[^\x00-\xff]

Commentary: can be used to compute the length of a string (a double-byte character length meter 2,ascii 1 characters)

Match Blank Line

\n\s*\r

Commentary: can be used to delete blank lines

Matching HTML tags

< (\s*?) [^>]*>.*?</\1><.*? />

Commentary: The online version is too bad, the above can only match the part of the complex nested tags still powerless

Match the trailing whitespace characters

^\s*\s*$

Commentary: A useful expression that can be used to delete white-space characters (including spaces, tabs, page breaks, and so on) at the end of a line at the beginning

Match email address

\w+ ([-+.] \w+) *@\w+ ([-.] \w+) *\.\w+ ([-.] \w+) *

Commentary: Form validation is useful

Matching URL URLs

[a-za-z]+://[^\s]*

Commentary: Online circulation of the version of the function is very limited, which can meet the basic requirements

Match account number is legal (beginning of letter, allow 5-16 bytes, allow alphanumeric underline)

^[a-za-z][a-za-z0-9_]{4,15}$

Commentary: Form validation is useful

Match domestic phone number

\D{3}-\D{8}\D{4}-\D{7}

Commentary: Match form such as 0511-4405222 or 021-87888822

Match Tencent QQ number

[1-9] [0-9] {4,}

Commentary: Tencent QQ number starting from 10000

Match China ZIP code

[1-9]\d{5} (?! \d)

Commentary: China postal code is 6 digits

Matching ID

\D{15}\D{18}

Commentary: China's ID card is 15-or 18-digit

Match IP Address

\d+\.\d+\.\d+\.\d+

Commentary: Useful when extracting IP addresses

Match a specific number

^[1-9]\d*$//Matching positive integer
^-[1-9]\d*$//matching negative integers
^-? [1-9]\d*$//matching integer
^[1-9]\d*0$//matching nonnegative integer (positive integer + 0)
^-[1-9]\d*0$//matching non positive integer (negative integer + 0)
^[1-9]\d*\.\d*0\.\d*[1-9]\d*$//matching positive floating-point numbers
^-([1-9]\d*\.\d*0\.\d*[1-9]\d*) $//matching negative floating-point number
^-? ([1-9]\d*\.\d*0\.\d*[1-9]\d*0?\.0+0) $//matching floating-point number
^[1-9]\d*\.\d*0\.\d*[1-9]\d*0?\.0+0$//matching nonnegative floating-point number (positive floating-point number + 0)
^ (-([1-9]\d*\.\d*0\.\d*[1-9]\d*)) 0?\.0+0$//matching non-positive floating-point numbers (negative floating-point number + 0)

Commentary: useful when dealing with large amounts of data, pay attention to corrections when applied

Match a specific string

^[a-za-z]+$//Match a string of 26 English letters
^[a-z]+$//Match a string of 26 uppercase letters
^[a-z]+$//Match string consisting of 26 lowercase letters
^[a-za-z0-9]+$//Match a string of numbers and 26 English letters
^\w+$//Match A string of numbers, 26 English letters, or underscores