regular expression 在线检测的网站

http://regexone.com/   学习网站

http://regexone.com/lesson/optional_characters?

http://regexone.com/lesson/capturing_groups

Task          Text                                      Capture Groups
Capture     file_record_transcript.pdf        file_record_transcript Success
Capture     file_07241999.pdf                  file_07241999 Success
Skip           testfile_fake.pdf.tmp

^(file.+).pdf

http://regexone.com/lesson/nested_groups?

Task Text Capture Groups
Capture Jan 1987 Jan 1987 1987
Capture May 1969 May 1969 1969
Capture Aug 2011 Aug 2011 2011

(D+(d+))

http://regexone.com/lesson/more_groups

1280x720  提取出1280 720

((d+)D(d+))

http://regexone.com/lesson/conditionals

Task Text
Match I love cats
Match I love dogs
Skip I love logs
Skip I love cogs

I love (cats|dogs)

regexper直接以图表的形式告诉你正则的筛选规则，regexr会逐个分析正则里面的字符含义

https://regexr.com/52sba

regexr会分析正则中每一部分的含义

(?=.*[A-Z])(?=.*[a-z])(?=.*[0-9])[a-zA-Z0-9]{8,15}    

https://regexper.com/#%2F%28%3F%3D.*%5BA-Z%5D%29%28%3F%3D.*%5Ba-z%5D%29%28%3F%3D.*%5B0-9%5D%29%5Ba-zA-Z0-9%5D%7B8%2C15%7D%2F

regexper会以图表的形式，显示这个正则达成的效果