CODEWITHSUNDEEP
phpregex
Anurag Singh
Anurag Singh

Reputation: 727

how to interpreter regular expression

I am new to regular expression. in order to study it i am referring to Mastering regular expression.

`My regular expression is`

    [a-z\s]{3,10}


and the input string is 

cat is the cat

I am checking this on https://regex101.com. in the output i am getting "cat is the " if i change the regular expression to [a-z\s]{1,10} than also i get the same result. so i am unable to get how this output is cumming.

Upvotes: 1

Views: 178

Answers (1)

Avinash Raj
Avinash Raj

Reputation: 174706

Noramlly regex engine would scan for a match in a string from left to right. Here, the actual regex is [a-z\s]{3,10} , it would match 10 chars of lowercase letters or spaces from the start since it was greedy. {3,10} repeats the previous token [a-z\s] min of three times and the max of 10 times. If the line contain lowercase letters or spaces of length 9, this regex would match that line also because 9 falls within the range 3, 10

[a-z\s]{1,10} also do the same job of matching 10 chars of lowercase letters or spaces from the start. {1,10} would repeat the previous token [a-z\s] minimum 1 time and the maximum of 10 times. So this also matches a line which has single character but the above regex matches a substring which must have at-least three characters.

Upvotes: 2

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