PHP introductory tutorial (20) Commonly used regular expressions in PHP

This article is the twentieth section of the PHP introductory tutorial. It introduces some commonly used regular expressions in PHP. Interested friends can refer to it.

Content of this section; Commonly used regular expressions in php

Regular expression matching Chinese characters: [u4e00-u9fa5] Comment: Matching Chinese is really a headache. With this expression, it will be easier

Match double-byte characters (including Chinese characters): [^x00-xff] Comment: Can be used to calculate the length of a string (the length of a double-byte character counts as 2, and the length of an ASCII character counts as 1)

Regular expression matching blank lines: ns*r Comment: Can be used to delete blank lines

Regular expression matching HTML tags: ]*>.*?1>|<.> Comment: The version circulating on the Internet is too bad. The above one can only match part of it, and it is still powerless for complex nested tags

Regular expression matching leading and trailing whitespace characters: ^s*|s*$ Comment: It can be used to delete whitespace characters (including spaces, tabs, form feeds, etc.) at the beginning and end of the line. It is a very useful expression

Regular expression matching email addresses: w+([-+.]w+)*@w+([-.]w+)*.w+([-.]w+)* Comment: Very useful for form verification

Regular expression matching URL: [a-zA-z]+://[^s]* Comment: The version circulating on the Internet has very limited functions. The above one can basically meet the needs

Whether the matching account is legal (starting with a letter, 5-16 bytes allowed, alphanumeric underscores allowed): ^[a-zA-Z][a-zA-Z0-9_]{4,15}$ Comment: Very useful for form verification

Matching domestic phone numbers: d{3}-d{8}|d{4}-d{7} Comment: Matching format is such as 0511-4405222 or 021-87888822

Match Tencent QQ number: [1-9][0-9]{4,} Comment: Tencent QQ account starts from 10000

Match Chinese postal code: [1-9]d{5}(?!d) Comment: China’s postal code is a 6-digit number

Matching ID card: d{15}|d{18} Comment: China’s ID card has 15 or 18 digits

Matching ip address: d+.d+.d+.d+ Comment: Useful when extracting IP address

Match specific numbers: ^[1-9]d*$ //Match positive integers ^-[1-9]d*$ //Match negative integers ^-?[1-9]d*$ //Match integers ^[1-9]d*|0$ // Match non-negative integers (positive integers + 0) ^-[1-9]d*|0$ //Match non-positive integers (negative integers + 0) ^[1-9]d*.d*|0.d*[1-9]d*$ //Match positive floating point numbers ^-([1-9]d*.d*|0.d*[1-9]d*)$ //Match negative floating point numbers ^-?([1-9]d*.d*|0.d*[1-9]d*|0?.0+|0)$ // Match floating point numbers ^[1-9]d*.d*|0.d*[1-9]d*|0?.0+|0$ //Match non-negative floating point numbers (positive floating point numbers + 0) ^(-([1-9]d*.d*|0.d*[1-9]d*))|0?.0+|0$　 //Match non-positive floating point numbers (negative floating point numbers + 0 ) Comment: Useful when processing large amounts of data, please pay attention to corrections when applying it

Match specific string: ^[A-Za-z]+$　 //Match a string consisting of 26 English letters ^[A-Z]+$ // Matches a string consisting of 26 uppercase English letters ^[a-z]+$　//Match a string consisting of 26 lowercase English letters ^[A-Za-z0-9]+$　 // Matches a string consisting of numbers and 26 English letters ^w+$　 // Matches a string consisting of numbers, 26 English letters, or underscores Comment: Some of the most basic and commonly used expressions