Regular expression Formulas Learning regular friends look at _ Regular expressions

It is the fortress that every programmer can't get around, only it is attacked. I think the reason is difficult, the first difficulty is to need memory, the second difficulty is to have abstract logical thinking.
Signed on the Internet too much of the introduction is a fierce essay, while looking at the understanding can help memory not. Also by Wubi font root table formula "managed to watch 32 Jin ..." Inspiration,
Try "Regular Expression mnemonics" also known as "regular Limerick", version 0.1, absolutely original, counterfeit must investigate,:
Note: This article is only for the study of the regular time in order to facilitate memory, can not replace the system and comprehensive learning process, errors and omissions, please correct me!
Is in fact also snobbish, cutting the point to put the money; (refers to the start symbol ^ and the end sign $)
Special symbols can not recognize, get a backward bar to guide; \* and other special symbols)
Behind the back with the small W, the number of letters to express; (\w with digital letters; \d with numbers)
The back of the bar with small d, only numbers to indicate;
Behind the bar with small a, alarm symbol beep;
Behind the bar with small B, word demarcation or backspace;
Behind the back with small t, the tab symbol is very clear;
The back of the bar with small r, carriage return symbol to know;
Behind the bar with small s, the space symbol is very important;
Lower case with the upper case, too much is really not;
Behind the back with the Big W, the letter number aside;
Behind the bar with big S, blank also on the sidelines;
Behind the bar with Big D, the number from the sidelines;
The back of the box with Big B, does not include the beginning and end;
Single character to repeat, three symbols to help; ）
0 Stars plus 1 to infinity, the question mark only 0 and 1; (* table 0-n;+ table 1-n;? Table 0-1 repeats)
More knowledge in curly braces, strong repetitive operation; ({n} {n} {n,m})
To repeat the string, enclose it in the garden; ((ABC) {3} indicates that the string "abc" Repeats 3 times)
Special set customization, brackets to help you;
Escape symbol not workable, one to line up;
There are so many of them out of line, please come and help me. ([1-5])
A sharp point is placed in brackets, and the definition of antisense is powerful; ([^a] refers to any character other than "a")
1 vertical function is not small, the two sides are replacing each other; (the keyboard is the same key as "\")
1 vertical energy used many times, complex definition is very convenient;
Garden brackets, multi-purpose;
A reverse reference to the specified group, with numeric rows corresponding to it; (The number "1" in "\b (\w+) \b\s+\1\b" refers to the preceding "(\w+)")
Support Group name customization, question mark with angle bracket, ("(? <word>\w+)" "\w+" defined as group, group named "Word")
The square bracket, uses many, the position designation depends on it;
Question mark equals string, positioned before the string ("\b\w+ (? =ing\b)" Locates the string before "ing")
To locate a string, insert a less than sign in the middle, ("(? <=\bsub) \w+\b" to the string following the "sub")
The question mark adds an exclamation point, followed by a string of strings;
Phper all know,! is to take the opposite meaning;
Back not with this string, all meet to report; ("\w*d!" OG) \w* "," dog "does not meet," do "in accordance with"
The question mark is less than the exclamation point followed by string strings;
The front does not put this string, all conforms to report;
Dot asterisk is greedy, add a question mark not greedy;
The plus question mark has the guarantee, at least repeat more than once;
Two question mark old rules, 0 times 1 times round;
Curly braces followed by a? , greed becomes not greedy;
There are a lot of not fit, waiting to be added later.
Some common regular expressions
"^\d+$"//non-negative Integer (positive integer + 0)
"^[0-9]*[1-9][0-9]*$"//Positive integer
"^ ((-\d+) | (0+)) $ "//non-positive integer (negative integer + 0)
"^-[0-9]*[1-9][0-9]*$"//Negative integer
"^-?\d+$"//Integer
"^\d+ (\.\d+)? $"//nonnegative floating-point number (positive float + 0)
"^ ([0-9]+\. [0-9]*[1-9][0-9]*) | ([0-9]*[1-9][0-9]*\. [0-9]+) | ([0-9]*[1-9][0-9]*)] $ "//Positive floating-point number
"^ ((-\d+ (\.\d+)?) | (0+ (\.0+)) $ "//non-positive floating-point number (negative floating-point number + 0)
^ (-([0-9]+\. [0-9]*[1-9][0-9]*) | ([0-9]*[1-9][0-9]*\. [0-9]+) | ([0-9]*[1-9][0-9]*))] $ "//negative floating-point number
"^ (-?\d+) (\.\d+)? $"//floating-point number
"^[a-za-z]+$"//A string of 26 English letters
"^[a-z]+$"//A string of 26 uppercase letters
"^[a-z]+$"///a string consisting of 26 lowercase letters
"^[a-za-z0-9]+$"//A string of numbers and 26 English letters
"^\w+$"//A string of numbers, 26 English letters, or underscores
"^[\w-]+ (\.[ \w-]+) *@[\w-]+ (\.[ \w-]+) +$ "//email address
"^[a-za-z]+://(\w+ (-\w+) *) (\. ( \w+ (-\w+) *)) * (\?\s*) $ "//url
/^ (D{2}|d{4})-((0 ([1-9]{1})) | ( 1[1|2])-(([0-2] ([1-9]{1})) | ( 3[0|1]) $///year-month-day
/^ ((0 ([1-9]{1})) | (1[1|2]) /(([0-2] ([1-9]{1})] | (3[0|1]) /(D{2}|d{4}) $///month/day/year
"^ ([w.] +) @ ([[0-9]{1,3}. [0-9] {1,3}. [0-9] {1,3}.) | (([w-]+.) +)) ([a-za-z]{2,4}| [0-9] {1,3}) (]?) $ "//emil
"(d+-)?" (d{4}-?d{7}|d{3}-?d{8}|^d{7,8}) (-d+)? " Phone number
"^ (d{1,2}|1dd|2[0-4]d|25[0-5]). (D{1,2}|1dd|2[0-4]d|25[0-5]). (D{1,2}|1dd|2[0-4]d|25[0-5]). (D{1,2}|1dd|2[0-4]d|25[0-5]) $ "//IP address
Matching regular expressions for Chinese characters: [\U4E00-\U9FA5]
Match Double-byte characters (including Chinese characters): [^\x00-\xff]
A regular expression that matches a blank row: \n[\s|] *\r
Regular expression matching HTML tags:/< (. *) >.*<\/\1>|< (. *) \/>/
Matching a regular expression with a trailing space: (^\s*) | (\s*$)
Regular expression matching an email address: \w+ ([-+.] \w+) *@\w+ ([-.] \w+) *\.\w+ ([-.] \w+) *
A regular expression that matches URL URLs: ^[a-za-z]+://(\\w+ (-\\w+) *) (\ \\w+ (-\\w+) *)) * (\\?\\s*)? $
Match account number is legal (beginning of letter, allow 5-16 bytes, allow alphanumeric underline): ^[a-za-z][a-za-z0-9_]{4,15}$
Match domestic phone number: (\d{3}-|\d{4}-)? (\d{8}|\d{7})?
Matching Tencent QQ Number: ^[1-9]*[1-9][0-9]*$
G: After reading the formula, there is a lot of content in total. But the example of a named group is wrong, and the description of the look is inaccurate, looking around without the character, is a match for the position, a peek after a certain point.