string — x y in REGEX

Question

Quick question. I have this string

string -- xy

I manage to get the constants down

/(string) (--) (X) (Y)/

my problem is x y. X and Y can be between 1-999 there's no leading zeros so no need to check on that.

Answer 1

string -- ([1-9]\d{0,2}) ([1-9]\d{0,2})

Debuggex Demo

Description

string --  matches the characters string --  literally (case sensitive)
1st Capturing group ([1-9]\d{0,2})
    [1-9] match a single character present in the list below
        1-9 a single character in the range between 1 and 9
    \d{0,2} match a digit [0-9]
        Quantifier: {0,2} Between 0 and 2 times, as many times as possible, giving back as needed [greedy]
      matches the character   literally
2nd Capturing group ([1-9]\d{0,2})
    [1-9] match a single character present in the list below
        1-9 a single character in the range between 1 and 9
    \d{0,2} match a digit [0-9]
        Quantifier: {0,2} Between 0 and 2 times, as many times as possible, giving back as needed [greedy]

Examples

string -- 1 999 //matches
string -- 10 02 //does not match
string -- 011 222 //does not match
string -- 111 222 //matches
string -- 41 2 //matches
string -- 999 1 //matches
string -- 1 1 //matches

Answer 2

您可以使用否定的前瞻表示避免前导零（和零）：

/(string) (--)(?!.* 0) (\d{1,3}) (\d{1,3})

Answer 3

For the number portion you should be checking [1-9][0-9]{0,2} . Otherwise you'll miss valid numbers such as 10 and 101 .