problem with NSString's stringByReplacingOccurrencesOfString

[Sebastian Reitenbach]

Hi,

I try to replace "'" with "\'", and also "\\" with "\\\\" using NSString's stringByReplacingOccurrencesOfString.

When I for example do this:
escapedFileName = [@"this is a string blah" stringByReplacingOccurrencesOfString:@"blah" withString:@"blubb"];
NSLog(@"escapedFileName: %@", escapedFileName);

Then it prints out:
escapedFileName: this is a string blubb

So far, so good.

but when I then try to:
escapedFileName = [@"this is a string' blah" stringByReplacingOccurrencesOfString:@"'" withString:@"\'"];
then the NSLog prints out:
escapedFileName: this is a string' blah

also when I try:
escapedFileName = [@"this is a string' blah" stringByReplacingOccurrencesOfString:@"'" withString:@"XXX"];
its still printing:
escapedFileName: this is a string' blah

also I have a problem when I try to escape \ characters:
escapedFileName = [@"this is a string\ blah" stringByReplacingOccurrencesOfString:@"blah" withString:@"blubb"];
prints:
escapedFileName: this is a string blubb
which replaced blah with blubb, but the backslash is also gone.

therefore, this doesn't work either:
escapedFileName = [@"this is a string\ blah" stringByReplacingOccurrencesOfString:@"\\" withString:@"\\\\"];
just strips the backslash, instead of replacing it. NSLog prints:
escapedFileName: this is a string blah

I'm now wondering what the heck I'm doing wrong here?
Any hit with a cluestick is appreciated.
Its gnustep-base 1.24.0 I am using.

cheers,
Sebastian

[Tom Davie]

On 11 Nov 2012, at 13:07, "Sebastian Reitenbach" <seba...@l00-bugdead-prods.de> wrote:

> Hi,
>
> I try to replace "'" with "\'", and also "\\" with "\\\\" using NSString's stringByReplacingOccurrencesOfString.
>
> When I for example do this:
> escapedFileName = [@"this is a string blah" stringByReplacingOccurrencesOfString:@"blah" withString:@"blubb"];
> NSLog(@"escapedFileName: %@", escapedFileName);
>
> Then it prints out:
> escapedFileName: this is a string blubb
>
> So far, so good.
>
> but when I then try to:
> escapedFileName = [@"this is a string' blah" stringByReplacingOccurrencesOfString:@"'" withString:@"\'"];
> then the NSLog prints out:
> escapedFileName: this is a string' blah

You have missed a quote, @"\'" is the string containing only a single quote, so you're asking it to replace quotes with the same quotes.
You wanted @"\'" in the first instance, and @"\\\'" in the second.

Tom Davie

[Sebastian Reitenbach]

Doh!. That works, many thanks.
With all my trials, I found this working:
escapedFileName = [@"this is a string' blah" stringByReplacingOccurrencesOfString:@"'" withString:@"XXXX"];
just to make sure, I retested with @"'" and with @"\'" as the first sring, and I get to the same result.
My first mail was a bit wrong here with that test I mentioned. That the @"'" worked for the first string, I did not
assumed I need that many backslashes for the second ;)

thanks Tom,

Sebastian

>
> Tom Davie