CODEWITHSUNDEEP
iosregexnsregularexpression
user1193256
user1193256

Reputation: 43

Validating IP address by regular expression - Unknown escape sequence

I am working on an iOS project that require using regular expression to validate ipv4 address.

I use following code

// only support ip4 currently
NSRegularExpression *regex = [NSRegularExpression
                              regularExpressionWithPattern:@"^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$"
                              options:0
                              error:nil];

NSUInteger numberOfMatches = [regex numberOfMatchesInString:IpString options:0 range:NSMakeRange(0, [IpString length])];
return (numberOfMatches==1?TRUE:FALSE);

XCode keep warning me "unknown escape sequence .". When return true when I type "1.3.6.-6" or "2.3.33".

How can I use dot(.) in regex? Thanks

Upvotes: 2

Views: 1975

Answers (1)

WDUK
WDUK

Reputation: 19030

You need to double backslash your ., as the first backslash is being interpreted by NSString, and it's looking for an escape character for . (which doesn't exist). Double backslashing (\\.) will cause the first backslash to escape the second backslash (which does exist), meaning you can use \ normally.

So for example, your regex will be:

@"^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$"

Upvotes: 4

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