Regular Expression to get substring from main string

Question

I am trying to get sub-string based on some pattern. trying to fetch first number which should not be in first character of main string.

Strings:

BRUSPAZ 8MG
BRUSPAZ MG
BRUSPAZ 10 MG
BRUSPAZ10 MG
AVAS 40
AVAS 40 TEST 2TABS
MICROCEF CV 200 TABS 
1CROCIN DS 240 MG / 5 ML SUSPENSION

My Regular Expression : /(\d+)( )?(MG)?/

Required Output:

@Sweeper sorry not in first word, it should not be first character — Juned Ansari
– Juned Ansari, Commented Dec 21, 2017 at 9:41
can you show us the expected outputs instead of an image, i can't check the image (company rules :() — Youcef LAIDANI
– Youcef LAIDANI, Commented Dec 21, 2017 at 9:43

Sweeper · Accepted Answer · 2017-12-27 11:47:43Z

2

This is the regex:

(?<!^)(\d+)(\s*MG)?

I changed the ( )? to \s* so as to account for other kinds of whitespace and more than one of them.
I added a (?<!^). This is a negative lookbehind, looking for ^ - the start of the string. Basically it says that "there should not be the start of the string before the digits".
If you run this regex line by line, and turning of the global modifier, you will not match the 5 in the last line.

If you want to match decimals as well, use this:

(?<!^)(\d+\.\d+)(\s*MG)?

answered Dec 21, 2017 at 9:45

Sweeper

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3 Comments

Try using a negative look ahead in your regular expression. Try looking that up. If you still can't figure out, ask a new question. @JunedAnsari

it does not extract float number eg. ALVACE 2.5MG

@JunedAnsari You should have said that in the question! Anyway, see the edit.