How to extract multiple numbers with regexp?

Question

matuser123 2016-2-16

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/268440-how-to-extract-multiple-numbers-with-regexp

编辑： Stephen23 2016-2-16

采纳的回答： Walter Roberson

在 MATLAB Online 中打开

I am trying to pull the ID from the following string.

'blah String XX blah'

where XX is the number that could be anything from 0 - 9999. I have tried the regular expression below but this only works for 0 - 9. Any ideas?

[aa,bb] = regexp(sss,'String (\d+)')

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Stephen23 2016-2-16

编辑：Stephen23 2016-2-16

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What do you mean that it "only works for 0 - 9"? Your code correctly matches any number of digits:

>> [aa,bb] = regexp('blah String 9999 blah','String (\d+)')
aa =
     6
bb =
    16

Is this not what you expect?

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Answer 1

Walter Roberson 2016-2-16

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https://ww2.mathworks.cn/matlabcentral/answers/268440-how-to-extract-multiple-numbers-with-regexp#answer_210040

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id = regexp(sss, '(?<=String\s+)(\d+)', 'match', 'once');

The result will be a cell array of string containing the matched string

If you want it more directly then

id = regexprep(sss, '(.*?String\s+)(\d+)(.*)', '$2', 'once');

The result would be a string directly.

The first version, the regexp version, is looking for digits proceeded by 'String' with the 'String' part marked up to indicate it is not to form part of the match.

The second version, the regexprep version, is matching on beginning of line to the first occurrence of 'String' as one group, matching on the digits as a second group, and matching to the end of the line as a third group, and is replacing the three matches with the content of the second group, thus effectively throwing away everything before and after the digits.