PHP regular expression theory

This article mainly introduces the theoretical knowledge of PHP regular expressions. Interested friends can refer to it. I hope it will be helpful to everyone.

1. Expression of check digits

1 Number:
^[0-9]*$
2 n-digit number:
^\d{ n}$
3 Number with at least n digits:
^\d{n,}$
4 Number with m-n digits:
^\d{m,n}$
5 Zero and numbers starting with non-zero:
^(0|[1-9][0-9]*)$
6 Numbers starting with non-zero and with up to two decimal places:
^([1 -9][0-9]*) (.[0-9]{1,2})?$
7 Positive or negative number with 1-2 decimal places:
^(\-)? \d (\.\d{1,2})?$
8 Positive numbers, negative numbers, and decimals:
^(\-|\ )?\d (\.\d )?$
9 Positive real numbers with two decimal places:
^[0-9] (.[0-9]{2})?$
10 Positive real numbers with 1~3 decimal places:
^ [0-9] (.[0-9]{1,3})?$
11 Non-zero positive integer:
^[1-9]\d*$ or ^([1-9 ][0-9]*){1,3}$ or ^\ ?[1-9][0-9]*$
12 Non-zero negative integer:
^\-[1-9 ][]0-9"*$ or ^-[1-9]\d*$
13 Non-negative integer:
^\d $ or ^[1-9]\d*|0$
14 Non-positive integer:
^-[1-9]\d*|0$ or ^((-\d )|(0 ))$
15 Non-negative floating point number:
^ \d (\.\d )?$ or ^[1-9]\d*\.\d*|0\.\d*[1-9]\d*|0?\.0 |0$
16 Non-positive floating point number:
^((-\d (\.\d )?)|(0 (\.0 )?))$ or ^(-([1-9]\d* \.\d*|0\.\d*[1-9]\d*))|0?\.0 |0$
17 Positive floating point number:
^[1-9]\d *\.\d*|0\.\d*[1-9]\d*$ or ^(([0-9] \.[0-9]*[1-9][0-9]* )|([0-9]*[1-9][0-9]*\.[0-9] )|([0-9]*[1-9][0-9]*))$
18 Negative floating point number:
^-([1-9]\d*\.\d*|0\.\d*[1-9]\d*)$ or ^(-(( [0-9] \.[0-9]*[1-9][0-9]*)|([0-9]*[1-9][0-9]*\.[0-9 ] )|([0-9]*[1-9][0-9]*)))$
19 Floating point number:
^(-?\d )(\.\d )?$ Or ^-?([1-9]\d*\.\d*|0\.\d*[1-9]\d*|0?\.0 |0)$

二, expression of check characters

1 Chinese characters:
^[\u4e00-\u9fa5]{0,}$
2 English and numbers:
^[A-Za-z0 -9] $ or ^[A-Za-z0-9]{4,40}$
3 All characters of length 3-20:
^.{3,20}$
4 by A string consisting of 26 English letters:
^[A-Za-z] $
5 A string consisting of 26 uppercase English letters:
^[A-Z] $
6 consisting of 26 A string consisting of lowercase English letters:
^[a-z] $
7 A string consisting of numbers and 26 English letters:
^[A-Za-z0-9] $
8 A string consisting of numbers, 26 English letters or underscores:
^\w $ or ^\w{3,20}$
9 Chinese, English, numbers including underscores:
^[\ u4E00-\u9FA5A-Za-z0-9_] $
10 Chinese, English, numbers but not including underscores and other symbols:
^[\u4E00-\u9FA5A-Za-z0-9] $ or ^[\ u4E00-\u9FA5A-Za-z0-9]{2,20}$
11 You can enter characters containing ^%&',;=?$\":
[^%&',;=? $\x22]
12 It is forbidden to enter characters containing ~:
[^~\x22]

3. Special requirement expressions

1. Email address:
^\w ([- .]\w )*@\w ([-.]\w )*\.\w ([-.]\w )*$
2, domain name:
[a-zA-Z0-9][-a-zA-Z0-9]{0,62}(/.[a-zA-Z0-9][-a-zA -Z0-9]{0,62}) /.?
3 , InternetURL:
[a-zA-z] ://[^\s]* or ^http://([\w -] \.) [\w-] (/[\w-./?%&=]*)?$
4, mobile phone number:
^(13[0-9]|14[5 |7]|15[0|1|2|3|5|6|7|8|9]|18[0|1|2|3|5|6|7|8|9])\d{8 }$
5, phone number ("XXX-XXXXXXX", "XXXX-XXXXXXXX", "XXX-XXXXXXX", "XXX-XXXXXXXX", "XXXXXXX" and "XXXXXXXX):
^(\(\ d{3,4}-)|\d{3.4}-)?\d{7,8}$
6 Domestic telephone number (0511-4405222, 021-87888822):
\d{3} -\d{8}|\d{4}-\d{7}
7, ID number:
15 or 18-digit ID number:
^\d{15}|\d{ 18}$
15-digit ID card:
^[1-9]\d{7}((0\d)|(1[0-2]))(([0|1|2] \d)|3[0-1])\d{3}$
18-digit ID card:
^[1-9]\d{5}[1-9]\d{3}( (0\d)|(1[0-2]))(([0|1|2]\d)|3[0-1])\d{4}$
8. Short ID number (Ending with numbers and letters x):
^([0-9]){7,18}(x|X)?$
or
^\d{8,18}|[0- 9x]{8,18}|[0-9X]{8,18}?$
9. Is the account legal (starting with a letter, 5-16 bytes allowed, alphanumeric underscores allowed):
^[ a-zA-Z][a-zA-Z0-9_]{4,15}$
10, password (starting with a letter, length between 6~18, can only contain letters, numbers and underscores):
^[a-zA-Z]\w{5,17}$
11, strong password (must contain a combination of uppercase and lowercase letters and numbers, special characters cannot be used, and the length is between 8-10) ：
^(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{8,10}$
12. Date format:
^ \d{4}-\d{1,2}-\d{1,2}
13. 12 months of the year (01～09 and 1～12):
^(0?[ 1-9]|1[0-2])$
14, 31 days of a month (01～09 and 1～31):
^((0?[1-9])|(( 1|2)[0-9])|30|31)$
15. Input format of money:
16. 1. There are four forms of money representation that we can accept: "10000.00" and "10,000.00 ", and "10000" and "10,000" without "cent":
^[1-9][0-9]*$
17. 2. This means any number that does not start with 0, However, this also means that a character "0" is not passed, so we use the following form:
^(0|[1-9][0-9]*)$
18, 3. A 0 Or a number that does not start with 0. We can also allow a negative sign at the beginning:
^(0|-?[1-9][0-9]*)$
19, 4. This means A 0 or a number that may be negative and does not start with 0. Let the user start with 0. Also remove the negative sign, because money cannot be negative. What we need to add next is to explain the possible decimal part ：
^[0-9] (.[0-9] )?$
20, 5. It must be noted that there should be at least 1 digit after the decimal point, so "10." is not passed , but "10" and "10.2" are passed:
^[0-9] (.[0-9]{2})?$
21. 6. In this way, we stipulate that there must be two decimal points after bit, if you think it is too harsh, you can do this:
^[0-9] (.[0-9]{1,2})?$
22. 7. This allows the user to write only one decimal places. Next we should consider commas in numbers. We can do this:
^[0-9]{1,3}(,[0-9]{3})*(.[0-9] {1,2})?$
23, 8.1 to 3 numbers, followed by any number of commas and 3 numbers, the commas become optional instead of required:
^([0-9] |[0 -9]{1,3}(,[0-9]{3})*)(.[0-9]{1,2})?$
24. Note: This is the final result, don’t Forget that " " can be replaced with "*" if you think an empty string is acceptable (strange, why?) Finally, don't forget to remove the backslash when using the function. Common mistakes are here
25, xml file:
^([a-zA-Z] -?) [a-zA-Z0-9] \\.[x|X][m|M][l|L]$
26. Regular expression of Chinese characters:
[\u4e00-\u9fa5]
27. Double-byte characters:
[^\x00-\xff]
(including Chinese characters , can be used to calculate the length of a string (the length of a double-byte character is counted as 2, and the length of an ASCII character is counted as 1))
28. Regular expression for blank lines: \n\s*\r (can be used to delete blanks Line)
29, regular expression of HTML tag:
<(\S*?)[^>]*>.*?|<.*? /> ; (The version circulating on the Internet is too bad. The above one is only partially effective and is still powerless for complex nested tags)
30. Regular expression for leading and trailing whitespace characters: ^\s*|\s*$ or (^ \s*)|(\s*$) (can be used to delete whitespace characters at the beginning and end of the line (including spaces, tabs, form feeds, etc.), a very useful expression)
31, Tencent QQ number: [1-9][0-9]{4,} (Tencent QQ number starts from 10000)
32, China postal code: [1-9]\d{5}(?!\d) (China’s postal code is 6 digits)
33. IP address: \d \.\d \.\d \.\d (useful when extracting IP address)

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