regular expression for matching substring with wildcard

Hi,

I would like to find the number of substrings in a string. The substring contains a unimportant character. For example:

string a = 'AFAFABBB' substring: 'AXA' (X represent an unimportant character)

If I use:

regexp(a,'A.A')

in matlab, it returns:

ans = 1

But the correct answer (for my case) should be 1 and 3. How to make that right?

Thanks!

Bo

Answer 1

[Walter Roberson]

regexp(a,'A(?=.A)')

See http://www.mathworks.com/help/matlab/matlab_prog/lookahead-assertions-in-regular-expressions.html