Why do strfind and regexp may lead to a different result?

Hi all,

I noticed that regexp and strfind may lead to different results. Here an example:

regexp('Infinitely Variable Transmission (IVT)','Infinitely Variable Transmission (IVT)')

Why does it occur?

Thanks

[Adam]

What is that an example of?

>> regexp('Infinitely Variable Transmission','Infinitely Variable Transmission')

ans =

     1

>> strfind('Infinitely Variable Transmission','Infinitely Variable Transmission')

ans =

     1

[pietro]

pardon, I pasted the wrong example.

[Stephen23]

@pietro: if you are planning on using regular expressions then you really need to understand the different meta-characters, such as parentheses. A good place to learn about regular expressions in MATLAB is to read the MATLAB documentation:

https://www.mathworks.com/help/matlab/matlab_prog/regular-expressions.html

Answer 1

[Adam]

regexp( 'Infinitely Variable Transmission (IVT)', 'Infinitely Variable Transmission \(IVT\)' )

works, but you have to escape the parenthesis as they have special meaning in a regexp expression.

if you look in

doc regexp

in the section headed 'Split Text at Delimiter Using split Keyword', there is an example of this for escaping the ^ symbol.

[pietro]

ahh you're right! Thanks

Answer 2

[Walter Roberson]

In the general case, regexp can return different results if the pattern includes metacharacters.

There is a routine that can be used to "escape" characters so that they are treated literally, but the routine name is not coming to mind at the moment.

[Walter Roberson]

regexptranslate() with the 'escape' option is suitable for this purpose.