Re: comparing Strings.
Re: comparing Strings.
- Subject: Re: comparing Strings.
- From: Graham Cox <email@hidden>
- Date: Tue, 7 Oct 2008 20:55:47 +1100
On 7 Oct 2008, at 7:46 pm, Gerriet M. Denkmann wrote:
On 7 Oct 2008, at 09:20, cGraham Cox <email@hidden> wrote:
On 7 Oct 2008, at 4:22 pm, Sandro Noel wrote:
i'm having a problem comparing some type of strings, for example the
one giving me a problem right now.
is let's say in my database i have 4 version of the same string .
"sandro's computer"
"sandro's_computer"
"sandros computer"
"sandros_computer"
I would like them to compare as being equal,
is there a way I can mingle with the comparing routine
to ask it to ignore some characters in the comparison?
First strip out the characters to be ignored:
NSString* tempString = [myString stringByTrimmingCharactersInSet:
[NSCharacterSet characterSetWithCharactersInString:@"'_ "]];
returns "sandroscomputer" given any of the above.
Are you quite sure?
The Tiger documentation says: "Returns a new string made by removing
from both ends of the receiver characters contained in a given
character set."
If this is still true, then the internal apostrophs would not get
removed.
But maybe I am misunderstanding the documentation.
DId not actually test this.
Whoops, I made a mistake.
I thought I'd seen a method for stripping characters in a set from a
string, and searching for it jumped on the stringByTrimming... method.
But as you correctly state, that's not right! However, I wasn't going
entirely mad, as I had seen the method, courtesy of a handy NSString
category by Alastair Houghton. I hope he won't mind my copying it in
below.
Apologies for the misleading info.
G.
@implementation NSString (RemovalOfCharsInSet)
/* Remove all characters from the specified set */
- (NSString *) stringByRemovingCharactersInSet:(NSCharacterSet*)
charSet options:(unsigned) mask
{
NSRange range;
NSMutableString* newString = [NSMutableString string];
unsigned len = [self length];
mask &= ~NSBackwardsSearch;
range = NSMakeRange (0, len);
while (range.length)
{
NSRange substringRange;
unsigned pos = range.location;
range = [self rangeOfCharacterFromSet:charSet options:mask
range:range];
if (range.location == NSNotFound)
range = NSMakeRange (len, 0);
substringRange = NSMakeRange (pos, range.location - pos);
[newString appendString:[self substringWithRange:substringRange]];
range.location += range.length;
range.length = len - range.location;
}
return newString;
}
- (NSString *) stringByRemovingCharactersInSet:(NSCharacterSet*)
charSet
{
return [self stringByRemovingCharactersInSet:charSet options:0];
}
- (NSString *) stringByRemovingCharacter:(unichar) character
{
NSCharacterSet *charSet = [NSCharacterSet
characterSetWithRange:NSMakeRange (character, 1)];
return [self stringByRemovingCharactersInSet:charSet];
}
@end
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