[Phure]

I have the following lines in my code:
(testString is an NSMutableString)

Code:
while ([testString rangeOfString:@"\n"].length>0) {
        [testString replaceCharactersInRange:[testString rangeOfString:@"\n"] withString:@"<br>"];
    }

This is a VERY slow solution. The one from the TextEdit sample code seems to be much faster, but it's too large for my simple application (IMHO). Any ideas how to speed this up?

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Phure (aka BlackMac.de)
He who knows does not talk - He who talks does not know!

[This message has been edited by Phure (edited 05-13-2001).]

[IamBob]

Code:
NSRange curRange;

for (curRange = [testString rangeOfString:@"\n"]; curRange.length>0; ) {
        [testString replaceCharactersInRange:curRange withString:@"<br>"];
    }

...maybe? It was typed in here so who knows. But it seems like searching for the range twice could be one hit to avoid. I'd do something like the above instead of calling -rangeOfString twice.

Also, if you look at the docs you'll notice -rangeOfString: calls -rangeOfString :options: which in turn calls -rangeOfString :options:range:. If you really want to optimize it you should avoid the chain calls like that - use -rangeOfString :options:range: instead of -rangeOfString.

Anyone else with anything to add?

[disabled smiles]

[This message has been edited by IamBob (edited 05-13-2001).]

[lindberg]

Yes, it's definitely inefficient -- think of all the realloc()ing and memory moving that needs to be done on each -replaceCharacters call if it's a big string.

Typically it's better to build up a new NSMutableString, searching through the first string iteratvely, and adding the necessary substrings to the new NSMutableString. I.e, whenever you find a match, add the substring since the last match then add the replacement string, wash, rinse, repeat. You can use -rangeOfString:options:range: to limit the range of the search to just the areas you haven't searched yet.

However, for the simple substitution you're doing, there's a much easier way:

newString = [[testString componentsSeparatedByString:@"\n"] componentsJoinedByString:@"<br>"];

[If you must modify the testString instance in place, then just add [testString setString:newString] afterwards.]

BTW, you might want to replace with @"<br>\n" so the resulting text is somewhat readable, but that's up to you :-)

[Phure]

"for" doesn't work. I get an endless loop, it does not reinitialize curRange, which is needed, because we get less \n s each time I replace one. Thanks though.
As for lindbergs idea: yes! I think I'm somewhat stupid, it looks so simple, even I could have thought of it :/ .
The result does not need to be readable, it's just meant for interpretation by the computer.

Thank you guys

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Phure (aka BlackMac.de)
He who knows does not talk - He who talks does not know!

[IamBob]

Cool. I didn't think the "for" would work but I wasn't sure. I just figured it showed what I was thinking in a compact/semi-understandable way.

Good to know there's an even easier way to do this though - that's cool.