regular expression in iOS

Question

I am looking for a regular expression to match the following -100..100:0.01. The meaning of this expression is that the value can increment by 0.01 and should be in the range -100 to 100.

Any help ?

Answer 1

You could use NSRegularExpression instead. It does support \b, btw, though you have to escape it in the string:

NSString *regex = @"\\b-?1?[0-9]{2}(\\.[0-9]{1,2})?\\b";

Though, I think \\W would be a better idea, since \\b messes up detecting the negative sign on the number.

A hopefully better example:

NSString *string = <...your source string...>;
NSError  *error  = NULL;

NSRegularExpression *regex = [NSRegularExpression 
  regularExpressionWithPattern:@"\\W-?1?[0-9]{2}(\\.[0-9]{1,2})?\\W"
                       options:0
                         error:&error];

NSRange range   = [regex rangeOfFirstMatchInString:string
                              options:0 
                              range:NSMakeRange(0, [string length])];
NSString *result = [string substringWithRange:range];

I hope this helps. :)

EDIT: fixed based on the below comment.

Answer 2

(\b|-)(100(\.0+)?|[1-9]?[0-9](\.[0-9]{1,2})?\b

Explanation:

(\b|-)      # word boundary or -
(           # Either match
 100        #  100
 (\.0+)?    #  optionally followed by .00....
|           # or match
 [1-9]?     #  optional "tens" digit
 [0-9]      #  required "ones" digit
 (          #  Try to match
  \.        #   a dot
  [0-9]{1,2}#   followed by one or two digits
 )?         #   all of this optionally
)           # End of alternation
\b          # Match a word boundary (make sure the number stops here).

Answer 3

Why do you want to use a regular expression? Why not just do something like (in pseudocode):

is number between -100 and 100?
  yes:
    multiply number by 100
    is number an integer?
      yes: you win!
      no:  you don't win!
  no:
    you don't win!