MATLAB Programming

3 Basic Program Components
ans =
Default
tok{:}
ans =
'a'
ans =
'b'
Tokens That Are Not Matched
For those tokens specified in the regular expression that have no match in the
string being evaluated, regexp and regexpi return an empty string ('') as
the token output, and an extent that marks the position in the string where
the token was expected.
The example shown here executes regexp on the path string str returned
from the MATLAB tempdir function. The regular expression expr includes
six token specifiers, one for each piece of the path string. The third specifier
[a-z]+ has no match in the string because this part of the path, Profiles,
begins with an uppercase letter:
str = tempdir
str =
C:\WINNT\Profiles\bpascal\LOCALS~1\Temp\
expr = ['([A-Z]:)\\(WINNT)\\([a-z]+)?.*\\' ...
'([a-z]+)\\([A-Z]+~\d)\\(Temp)\\'];
[tok ext] = regexp(str, expr, 'tokens', 'tokenExtents');
When a token is not found in a string, MATLAB still returns a token string
and token extent. The returned token string is an empty character string
(''). The first number of the extent is the string index that marks where the
token was expected, and the second number of the extent is equal to one
less than the first.
In the case of this example, the empty token is the third specified in the
expression, so the third token string returned is empty:
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