NSString strip regular \ escape characters how?

Question

I need an efficient piece of code that strips escape characters. This is regular escapes not HTML escape characters.

Example: "\"", "\\\\", "\", "\\"

I want a general algorithm to strip any kind of escape sequences.

Could use any utility like regular expression.

  (NSString*) unescape:(NSString*) string {

      ....
  }

This is the answer I wrote:

-(NSString*) unescape:(NSString*) string
{

    for(int i = 0; i < string.length; i++) {
        char a = [string characterAtIndex:i];
        if([string characterAtIndex:i] == '\\' ) {
            string = [string stringByReplacingCharactersInRange:NSMakeRange(i,1) withString:@""];
        }

    }
    return string;
}

What kind of escape characters? There are a lot types of escaping systems. C-style? HTML? What? — , Nov 16 '12 at 21:10
@userXXX in this case you can just replace `"\\\""` with `"\""`, etc. — , Nov 16 '12 at 21:45
I want a general algorithm to strip any kind of escape sequences. — user1307179, Nov 16 '12 at 22:02
How about a regex like this to strip from string, `\\[bntr\\\\"]` — iDev, Nov 17 '12 at 00:43

score 2 · Answer 1 · edited Mar 07 '13 at 11:39

2

Try to use below code for HTML escape

(NSString*) unescape:(NSString*) string 
{
    return [string stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
}

for regular Escape

(NSString*) unescape:(NSString*) string 
{    
    return [string stringByReplacingOccurrencesOfString:@"\\\"" withString:@"\""];
}

edited Mar 07 '13 at 11:39

Artem Shmatkov

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answered Nov 16 '12 at 21:20

1

I want a general algorithm that strips any kind of escape sequences. Not just "\"". Another example: "\\\\\\\\" – user1307179 Nov 16 '12 at 21:51
This will not work correctly if a string contains "\\", i.e. two backslashes, which is common in escaped strings. – Thomas Tempelmann May 23 '19 at 09:26

esreli · Answer 2 · 2012-11-17T01:12:15.073

1

The best method that you should use is:

- (NSString *)stringByTrimmingCharactersInSet:(NSCharacterSet *)set

You would call it using:

string = [string stringByTrimmingCharactersInSet:[NSCharacterSet newlineCharacterSet]];

edited Nov 17 '12 at 01:12

answered Nov 17 '12 at 01:02

esreli

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score 0 · Answer 3 · edited Mar 11 '13 at 17:58

0

If its URL Encoded, you are probably looking for:

stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding

edited Mar 11 '13 at 17:58

nalply

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answered Nov 16 '12 at 21:14

jeremy

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score 0 · Answer 4 · answered Nov 17 '12 at 00:57

If you want to use regex, you can try with regex pattern \\[bntr\\\\"]. Or use any required regex pattern here.

NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:
                              @"\\[bntr\\\\"]" options:0 error:nil];

[regex replaceMatchesInString:str options:0 range:NSMakeRange(0, [str length]) withTemplate:@""];

holex · Answer 5 · 2013-03-07T11:53:15.330

0

I apoligize for my answer...

NSString *_string = @"\\\\ dfsdg \\ tr\\\\t \\\\\\tw\\\\\\\\w\\ t\\ \\\\ \\ \\\\\\  rret\\    \\\\ \\\\\\\\";
NSLog(@"%@", [_string stringByReplacingOccurrencesOfString:@"\\" withString:@""]);

result is:

 dfsdg  trt tww t     rret

edited Mar 07 '13 at 11:53

answered Mar 07 '13 at 11:46

holex

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Yuliani Noriega · Answer 6 · 2013-03-11T20:12:43.850

-1

Hope this helps:

-(NSString *)unescape:(NSString *)string 
{
    if ([string rangeOfString:@"\\"].location != NSNotFound)
    {
        [string stringByReplacingCharactersInRange:@"\\" withString:@"\\"];
    }
    else if ([string rangeOfString:@"\\\\"].location != NSNotFound)
    {
        [string stringByReplacingCharactersInRange:@"\\\\" withString:@"\\"];
    }
    else if ([string rangeOfString:@"\\\\"].location != NSNotFound)
    {
        [string stringByReplacingCharactersInRange:@"\\\\" withString:@"\\"];
    }
}

edited Mar 11 '13 at 20:12

answered Nov 16 '12 at 21:53

Yuliani Noriega

1,085
12
23

No that's not all i want to do. I would have done that myself if it is that simple – user1307179 Nov 16 '12 at 21:55
that doesn't help. I need either a brute force way to scan every single characters from start to end... OR.. use regular expression.... so if you see "\\\\" you replace it with length of ("\\\\") divided by two number of \ characters..... "User regular expression to find/replace" – user1307179 Nov 16 '12 at 22:29

NSString strip regular \ escape characters how?

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