CODEWITHSUNDEEP
regex
Graham
Graham

Reputation: 8151

how to match a character unless it is part of a specific string with regex

Don't know how to explain this, so an example:

xx_xx -> matches because of the underscore -> .*_.*

xx_t_xx -> dont want this to match as _t_ is an exception I want to ignore

xx_t_xx_xx -> matches as there is an underscore that is not part of the string _t_

xx_t_xx_t_xx -> no match

_t_ -> no match

_ -> match

_t__ -> match

So match underscores unless it is part of the string _t_

Can that be done with regex?

Upvotes: 0

Views: 60

Answers (3)

Pratik Bhoir
Pratik Bhoir

Reputation: 2144

Finally Done, checked all your conditions. works fine Try this, it accepts any single character. This will definitely work for you

^([^_]|(_t_))*_([^_]|(_t_))*$

Upvotes: 1

Ulugbek Umirov
Ulugbek Umirov

Reputation: 12797

If your language supports negative lookbehind and negative lookahead, you can use (?<!_t)_(?!t_) regex. Basically you search for _ not preceded by _t and not followed by t_

Upvotes: 1

aelor
aelor

Reputation: 11116

okay

use this : ^[a-z]+_[a-z]+$

this will only match one underscore

i.e it will match xx_xx but not xx_t_xx

try this in your console : 

var str = "xx_xx";
var res = /^[a-z]+_[a-z]+$/.test(str);
console.log(res);

and yes one more thing . LEARN REGEX its very helpful. you will like to start from regexone

Upvotes: 2

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