MATLAB Programming

Regular Expressions
specify three tokens in an expression (that is, if you enclose three parts of
the expression in parentheses), then you would refer to these tokens in a
condition statement as 1, 2, and3.
The following example uses the conditional statement (?(1)her|his) to
match the string regardless of the gender used. You could translate this into
the phrase, “if token 1 is found (i.e., Mr is followed by the letter s), then
match her, else match his.”
expr = 'Mr(s?)\..*?(?(1)her|his) son';
[mat tok] = regexp('Mr. Clark went to see his son', ...
expr, 'match', 'tokens')
mat =
'Mr. Clark went to see his son'
tok =
{1x2 cell}
tok{:}
ans =
''
'his'
In the second part of the example, the token s is found and MATLAB matches
the word her:
[mat tok] = regexp('Mrs. Clark went to see her son', ...
expr, 'match', 'tokens')
mat =
'Mrs. Clark went to see her son'
tok =
{1x2 cell}
tok{:}
ans =
's'
'her'
Note When referring to a token within a condition, use just the number of
the token. For example, refer to token 2 by using the number 2 alone, and
not \2 or $2.
3-57