I have an input on the form that should only accept the following formats:
Examples
The minimum size must be 3 and maximum 9, and must always follow the pattern 1 digit and 2 letters. It should not be accepted for example 1AB2 or 1AB2C.
I did so:
[0-9]{1}[a-zA-Z]{2}
But in this case it only works for the first example I put, I do not know how to repeat the pattern.
If you want the "1 digit, 2 letter" pattern to be repeated a maximum of 3 times, you can use the {} quantizer, indicating the minimum and maximum number of times. In this case, the minimum is 1, and the maximum is 3, then it would look like:
(\d[a-zA-Z]{2}){1,3}
Notice that I changed [0-9] to \d , as are equivalent * (both are for digits). And I removed {1} because it is redundant, since "1 repetition" is the default.
And the parentheses are necessary, since the whole "1 digit, 2 letters" should be repeated 1 to 3 times.
You can see this regex running here .
* Usually < [0-9] and \d are equivalent. The only detail is that depending on the language / engine / configuration, \d may also correspond to other characters representing digits , such as ٠١٢٣٤٥٦٧٨٩ characters (see this answer for more details).