Several things here. Firstly your regular expression matches the whole string
because you have a '*' after the capture group. Putting a '*' after a capture
group doesn't make the RE match multiple times and make multiple captures, it
just makes that group repeat and the capture group will end up with the last
value captured.
eg in your case below, if you'd looked at the result of the regular expression
match instead of just the count, you'd see it's captured the entire string, has
two ranges, the first of which is the whole string and the second of which is
the last 4 characters "Home", the matching is like this
number -> matches [a-z]+
Of -> matches [A-Z][a-z]+ and captures into \1 and repeats
because of the *
Elements -> matches [A-Z][a-z]+ and captures into \1 and repeats
because of the *
At -> matches [A-Z][a-z]+ and captures into \1 and repeats
because of the *
Home -> matches [A-Z][a-z]+ and captures into \1
The whole string is matched and the result will contain 'Home' as the last
value captured in that one capture group.
You just want the RegEx to be
[A-Z][a-z]+
Which will capture each string starting with a capital letter followed by small
letters. That you'll find captures 4 times on your string.
Couple of other things, what's all that case insensitive stuff doing in there?
Because you are specifying a character class it doesn't matter but it's
misleading as you are trying to be case sensitive.
Your idea for an expression will fail on something like this numberOfPeasInAPod
which I assume you would want to change to number_of_peas_in_a_pod, because
there are no small letters following the 'A', so a modificiation to the RE I
suggested above would be
[A-Z][a-z]*
which that works for the above case.
Finally why are you using a Regular Expression for this at all, it's a bit
heavyweight isn't it? You could use normal NSString methods to go find capital
letters and then just replace the capital letter with _<lowercase version>
On 17-Oct-2010, at 2:38 PM, Devraj Mukherjee wrote:
> Hi all,
>
> I am trying to use Regular Expressions to match uppercase letters in
> strings like "numberOfNames" which I want to replace with
> number_of_names. Code sample
>
>
> NSError *error = NULL;
> NSRegularExpression *regex = [NSRegularExpression
> regularExpressionWithPattern:@"[a-z]+([A-Z][a-z]+)*"
>
>
> options:NSRegularExpressionAllowCommentsAndWhitespace
>
>
> error:&error];
>
>
> NSMutableString *aStr = [NSMutableString
> stringWithString:@"numberOfElementsAtHome"];
> NSLog(@"%i", [regex numberOfMatchesInString:aStr
>
> options:NSRegularExpressionCaseInsensitive
>
> range:NSMakeRange(0, [aStr length])]);
>
> In all cases my regular expressions matches one occurrence.
>
> Can anyone see what I might be getting wrong?
>
> May be I am using parameters in the regex string that
> NSRegularExpression doesn't support?
>
> Thanks a lot.
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