正则表达式：在字符串开头重复模式

Question

For example, consider the following string: "apple1: apple2: apple3: some random words here apple4:"

I want to match only apple1, apple2 and apple3 but not apple4. I am having a hard time to figure out how to archive this.

Any help is appreciated.

Thanks.

Answer 1

If you are using .net you can match the below pattern and then use the Captures property of the group to get all the different apples matched along the way.

(?:(apple\d).*?){3}

If you only want to match the first one:

apple\d

Sweet and simple. Just call match on this once.

Answer 2

From your comment, it sounds like you want to match the occurrences of apple followed by a digit throughout the string except an occurrence of apple followed by a digit at the end of the string.

>>> import re
>>> text    = 'apple1: apple2: apple3: some random words here apple4:'
>>> matches = re.findall(r'(\bapple\d+):(?!$)', text)

['apple1', 'apple2', 'apple3']

Answer 3

So, maybe something like this:

^([A-Za-z]+)[^A-Za-z]+(\1[^A-Za-z]+)+

http://regexr.com/38vvb

Answer 4

Sorry guys, I did not format my question properly, it wasn't clear.

I found the solution:

r'\s*((apple)\d+[ \:\,]*)+'

Thanks for all your help!