Why doesn't [01-12] range work as expected?

I'm trying to use the range pattern [01-12] in regex to match two digit mm, but this doesn't work as expected.

edited Jul 8 '15 at 5:36

Jerry

58.2k1068102

asked Jun 30 '10 at 10:14

DEACTIVATIONPRESCRIPTION.NET

4922610

7

You're matching characters, not character sequences. Basically, you're matching against 0, 1 to 1, and 2 (ie. 0, 1 and 2). Consider this: [a-z0-9], this matches all the lowercase letter, and all the digits, but only as a single character.

– Lasse Vågsæther Karlsen
Jun 30 '10 at 10:18

fwiw I created a javascript tool that creates a highly optimized regex from two inputs (min/max) github.com/jonschlinkert/to-regex-range

– jonschlinkert
Apr 21 '17 at 10:18

0[1-9]|1[0-2] -> 0|1|2 -> s in a regex denote a character class. If no ranges are specified, it implicitly ors every character.

– Badri Gs
Aug 4 '17 at 5:08

Do you need to match it with pure regex? If not, you can: 1.) just simply use the d+ pattern, 2.) convert the matched strings to numbers in your code. and then, 3.) check the number range like if(num >= 0 && num <= 12){ /*do something*/ }. It's so much faster and flexible.

– acegs
Apr 26 '18 at 5:47

add a comment |

I'm trying to use the range pattern [01-12] in regex to match two digit mm, but this doesn't work as expected.

edited Jul 8 '15 at 5:36

Jerry

58.2k1068102

asked Jun 30 '10 at 10:14

DEACTIVATIONPRESCRIPTION.NET

4922610

7

You're matching characters, not character sequences. Basically, you're matching against 0, 1 to 1, and 2 (ie. 0, 1 and 2). Consider this: [a-z0-9], this matches all the lowercase letter, and all the digits, but only as a single character.

– Lasse Vågsæther Karlsen
Jun 30 '10 at 10:18

fwiw I created a javascript tool that creates a highly optimized regex from two inputs (min/max) github.com/jonschlinkert/to-regex-range

– jonschlinkert
Apr 21 '17 at 10:18

0[1-9]|1[0-2] -> 0|1|2 -> s in a regex denote a character class. If no ranges are specified, it implicitly ors every character.

– Badri Gs
Aug 4 '17 at 5:08

Do you need to match it with pure regex? If not, you can: 1.) just simply use the d+ pattern, 2.) convert the matched strings to numbers in your code. and then, 3.) check the number range like if(num >= 0 && num <= 12){ /*do something*/ }. It's so much faster and flexible.

– acegs
Apr 26 '18 at 5:47

add a comment |

I'm trying to use the range pattern [01-12] in regex to match two digit mm, but this doesn't work as expected.

edited Jul 8 '15 at 5:36

Jerry

58.2k1068102

asked Jun 30 '10 at 10:14

DEACTIVATIONPRESCRIPTION.NET

4922610

I'm trying to use the range pattern [01-12] in regex to match two digit mm, but this doesn't work as expected.

regex

edited Jul 8 '15 at 5:36

Jerry

58.2k1068102

asked Jun 30 '10 at 10:14

DEACTIVATIONPRESCRIPTION.NET

4922610

edited Jul 8 '15 at 5:36

Jerry

58.2k1068102

asked Jun 30 '10 at 10:14

DEACTIVATIONPRESCRIPTION.NET

4922610

edited Jul 8 '15 at 5:36

Jerry

58.2k1068102

edited Jul 8 '15 at 5:36

Jerry

58.2k1068102

edited Jul 8 '15 at 5:36

Jerry

58.2k1068102

asked Jun 30 '10 at 10:14

DEACTIVATIONPRESCRIPTION.NET

4922610

asked Jun 30 '10 at 10:14

DEACTIVATIONPRESCRIPTION.NET

4922610

asked Jun 30 '10 at 10:14

DEACTIVATIONPRESCRIPTION.NET

4922610

7

You're matching characters, not character sequences. Basically, you're matching against 0, 1 to 1, and 2 (ie. 0, 1 and 2). Consider this: [a-z0-9], this matches all the lowercase letter, and all the digits, but only as a single character.

– Lasse Vågsæther Karlsen
Jun 30 '10 at 10:18

fwiw I created a javascript tool that creates a highly optimized regex from two inputs (min/max) github.com/jonschlinkert/to-regex-range

– jonschlinkert
Apr 21 '17 at 10:18

0[1-9]|1[0-2] -> 0|1|2 -> s in a regex denote a character class. If no ranges are specified, it implicitly ors every character.

– Badri Gs
Aug 4 '17 at 5:08

Do you need to match it with pure regex? If not, you can: 1.) just simply use the d+ pattern, 2.) convert the matched strings to numbers in your code. and then, 3.) check the number range like if(num >= 0 && num <= 12){ /*do something*/ }. It's so much faster and flexible.

– acegs
Apr 26 '18 at 5:47

add a comment |

7

You're matching characters, not character sequences. Basically, you're matching against 0, 1 to 1, and 2 (ie. 0, 1 and 2). Consider this: [a-z0-9], this matches all the lowercase letter, and all the digits, but only as a single character.

– Lasse Vågsæther Karlsen
Jun 30 '10 at 10:18

fwiw I created a javascript tool that creates a highly optimized regex from two inputs (min/max) github.com/jonschlinkert/to-regex-range

– jonschlinkert
Apr 21 '17 at 10:18

0[1-9]|1[0-2] -> 0|1|2 -> s in a regex denote a character class. If no ranges are specified, it implicitly ors every character.

– Badri Gs
Aug 4 '17 at 5:08

Do you need to match it with pure regex? If not, you can: 1.) just simply use the d+ pattern, 2.) convert the matched strings to numbers in your code. and then, 3.) check the number range like if(num >= 0 && num <= 12){ /*do something*/ }. It's so much faster and flexible.

– acegs
Apr 26 '18 at 5:47

You're matching characters, not character sequences. Basically, you're matching against 0, 1 to 1, and 2 (ie. 0, 1 and 2). Consider this: [a-z0-9], this matches all the lowercase letter, and all the digits, but only as a single character.

– Lasse Vågsæther Karlsen
Jun 30 '10 at 10:18

fwiw I created a javascript tool that creates a highly optimized regex from two inputs (min/max) github.com/jonschlinkert/to-regex-range

– jonschlinkert
Apr 21 '17 at 10:18

0[1-9]|1[0-2] -> 0|1|2 -> s in a regex denote a character class. If no ranges are specified, it implicitly ors every character.

– Badri Gs
Aug 4 '17 at 5:08

Do you need to match it with pure regex? If not, you can: 1.) just simply use the d+ pattern, 2.) convert the matched strings to numbers in your code. and then, 3.) check the number range like if(num >= 0 && num <= 12){ /*do something*/ }. It's so much faster and flexible.

– acegs
Apr 26 '18 at 5:47

add a comment |

7 Answers
7

active

oldest

votes

151

You seem to have misunderstood how character classes definition works in regex.

To match any of the strings 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, or 12, something like this works:

0[1-9]|1[0-2]

References

regular-expressions.info/Character Classes
- Numeric Ranges (have many examples on matching strings interpreted as numeric ranges)

Explanation

A character class, by itself, attempts to match one and exactly one character from the input string. [01-12] actually defines [012], a character class that matches one character from the input against any of the 3 characters 0, 1, or 2.

The - range definition goes from 1 to 1, which includes just 1. On the other hand, something like [1-9] includes 1, 2, 3, 4, 5, 6, 7, 8, 9.

Beginners often make the mistakes of defining things like [this|that]. This doesn't "work". This character definition defines [this|a], i.e. it matches one character from the input against any of 6 characters in t, h, i, s, | or a. More than likely (this|that) is what is intended.

References

regular-expressions.info/Brackets for Grouping and Alternation with the vertical bar

How ranges are defined

So it's obvious now that a pattern like between [24-48] hours doesn't "work". The character class in this case is equivalent to [248].

That is, - in a character class definition doesn't define numeric range in the pattern. Regex engines doesn't really "understand" numbers in the pattern, with the exception of finite repetition syntax (e.g. a{3,5} matches between 3 and 5 a).

Range definition instead uses ASCII/Unicode encoding of the characters to define ranges. The character 0 is encoded in ASCII as decimal 48; 9 is 57. Thus, the character definition [0-9] includes all character whose values are between decimal 48 and 57 in the encoding. Rather sensibly, by design these are the characters 0, 1, ..., 9.

Another example: A to Z

Let's take a look at another common character class definition [a-zA-Z]

In ASCII:

A = 65, Z = 90

a = 97, z = 122

This means that:

[a-zA-Z] and [A-Za-z] are equivalent

In most flavors, [a-Z] is likely to be an illegal character range
- because a (97) is "greater than" than Z (90)

[A-z] is legal, but also includes these six characters:
- [ (91), (92), ] (93), ^ (94), _ (95), ``` (96)

7 Answers
7

active

oldest

votes

7 Answers
7

active

oldest

votes

151

You seem to have misunderstood how character classes definition works in regex.

To match any of the strings 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, or 12, something like this works:

0[1-9]|1[0-2]

References

regular-expressions.info/Character Classes
- Numeric Ranges (have many examples on matching strings interpreted as numeric ranges)

Explanation

The - range definition goes from 1 to 1, which includes just 1. On the other hand, something like [1-9] includes 1, 2, 3, 4, 5, 6, 7, 8, 9.

References

regular-expressions.info/Brackets for Grouping and Alternation with the vertical bar

How ranges are defined

So it's obvious now that a pattern like between [24-48] hours doesn't "work". The character class in this case is equivalent to [248].

Another example: A to Z

Let's take a look at another common character class definition [a-zA-Z]

In ASCII:

A = 65, Z = 90

a = 97, z = 122

This means that:

[a-zA-Z] and [A-Za-z] are equivalent

In most flavors, [a-Z] is likely to be an illegal character range
- because a (97) is "greater than" than Z (90)

[A-z] is legal, but also includes these six characters:
- [ (91), (92), ] (93), ^ (94), _ (95), ``` (96)

References

regular-expressions.info/Character Classes
- Numeric Ranges (have many examples on matching strings interpreted as numeric ranges)

Explanation

The - range definition goes from 1 to 1, which includes just 1. On the other hand, something like [1-9] includes 1, 2, 3, 4, 5, 6, 7, 8, 9.

References

regular-expressions.info/Brackets for Grouping and Alternation with the vertical bar

How ranges are defined

So it's obvious now that a pattern like between [24-48] hours doesn't "work". The character class in this case is equivalent to [248].

Another example: A to Z

Let's take a look at another common character class definition [a-zA-Z]

In ASCII:

A = 65, Z = 90

a = 97, z = 122

This means that:

[a-zA-Z] and [A-Za-z] are equivalent

In most flavors, [a-Z] is likely to be an illegal character range
- because a (97) is "greater than" than Z (90)

[A-z] is legal, but also includes these six characters:
- [ (91), (92), ] (93), ^ (94), _ (95), ``` (96)

References

regular-expressions.info/Character Classes
- Numeric Ranges (have many examples on matching strings interpreted as numeric ranges)

Explanation

The - range definition goes from 1 to 1, which includes just 1. On the other hand, something like [1-9] includes 1, 2, 3, 4, 5, 6, 7, 8, 9.

References

regular-expressions.info/Brackets for Grouping and Alternation with the vertical bar

How ranges are defined

So it's obvious now that a pattern like between [24-48] hours doesn't "work". The character class in this case is equivalent to [248].

Another example: A to Z

Let's take a look at another common character class definition [a-zA-Z]

In ASCII:

A = 65, Z = 90

a = 97, z = 122

This means that:

[a-zA-Z] and [A-Za-z] are equivalent

In most flavors, [a-Z] is likely to be an illegal character range
- because a (97) is "greater than" than Z (90)

[A-z] is legal, but also includes these six characters:
- [ (91), (92), ] (93), ^ (94), _ (95), ``` (96)

References

regular-expressions.info/Character Classes
- Numeric Ranges (have many examples on matching strings interpreted as numeric ranges)

Explanation

The - range definition goes from 1 to 1, which includes just 1. On the other hand, something like [1-9] includes 1, 2, 3, 4, 5, 6, 7, 8, 9.

References

regular-expressions.info/Brackets for Grouping and Alternation with the vertical bar

How ranges are defined

So it's obvious now that a pattern like between [24-48] hours doesn't "work". The character class in this case is equivalent to [248].

Another example: A to Z

Let's take a look at another common character class definition [a-zA-Z]

In ASCII:

A = 65, Z = 90

a = 97, z = 122

This means that:

[a-zA-Z] and [A-Za-z] are equivalent

In most flavors, [a-Z] is likely to be an illegal character range
- because a (97) is "greater than" than Z (90)

[A-z] is legal, but also includes these six characters:
- [ (91), (92), ] (93), ^ (94), _ (95), ``` (96)

Related questions

is the regex [a-Z] valid and if yes then is it the same as [a-zA-Z]

edited May 23 '17 at 12:03

Community♦

answered Jun 30 '10 at 10:15

polygenelubricants

282k101505592

edited May 23 '17 at 12:03

Community♦

edited May 23 '17 at 12:03

Community♦

edited May 23 '17 at 12:03

Community♦

answered Jun 30 '10 at 10:15

polygenelubricants

282k101505592

answered Jun 30 '10 at 10:15

polygenelubricants

282k101505592

answered Jun 30 '10 at 10:15

polygenelubricants

282k101505592

For me, I was looking for months without prefixing with 0 if single digit. And I used this ([1-9]|(1[0-2])) and it works.

– bunjeeb
Feb 18 '17 at 0:39

2

Important to note: If you find this page wanting a solution for your number range that only has single digits before getting to the tens, 0[1-9]|1[0-2] won't work. Changing it to the logical next step [1-9]|1[0-2] doesn't work either for understandable reasons (It matches the 1 only in 10, 11, and 12). Had to use b(?:[0-9]|1[0-1])b to prevent that. b's makes sure regex matches word (or in this case number) boundaries (^ & $ didn't); brackets make the or (|) consider the other side of it; and finally ?: is to not create a submatch with the use of the brackets.

– user66001
Apr 13 '17 at 19:05

@polygenelubricants : "1,2,3,4,5,6,7,8,9,10,17,18".match(/^(([1-9]|1[0-7]),?)+$/g ) Can you please tell me why is this JS regex matches above 17?

– edam
Jan 24 '18 at 13:39

@edam - polygenelubricants could, and so could I, but then we'd be answering a questi… wait… is this a question you are asking in a comment? There are rulez on this site ;) Ask a Question if you have a new question. Comments are only for critiquing and asking for clarification, and for responding to those.

– robinCTS
Mar 9 '18 at 4:42

@edam Oh, I see. You did re-ask it as a question an hour later. That's great! However, it would probably be a good idea to delete your comment here.

– robinCTS
Mar 13 '18 at 11:11

add a comment |

For me, I was looking for months without prefixing with 0 if single digit. And I used this ([1-9]|(1[0-2])) and it works.

– bunjeeb
Feb 18 '17 at 0:39

2

Important to note: If you find this page wanting a solution for your number range that only has single digits before getting to the tens, 0[1-9]|1[0-2] won't work. Changing it to the logical next step [1-9]|1[0-2] doesn't work either for understandable reasons (It matches the 1 only in 10, 11, and 12). Had to use b(?:[0-9]|1[0-1])b to prevent that. b's makes sure regex matches word (or in this case number) boundaries (^ & $ didn't); brackets make the or (|) consider the other side of it; and finally ?: is to not create a submatch with the use of the brackets.

– user66001
Apr 13 '17 at 19:05

@polygenelubricants : "1,2,3,4,5,6,7,8,9,10,17,18".match(/^(([1-9]|1[0-7]),?)+$/g ) Can you please tell me why is this JS regex matches above 17?

– edam
Jan 24 '18 at 13:39

@edam - polygenelubricants could, and so could I, but then we'd be answering a questi… wait… is this a question you are asking in a comment? There are rulez on this site ;) Ask a Question if you have a new question. Comments are only for critiquing and asking for clarification, and for responding to those.

– robinCTS
Mar 9 '18 at 4:42

@edam Oh, I see. You did re-ask it as a question an hour later. That's great! However, it would probably be a good idea to delete your comment here.

– robinCTS
Mar 13 '18 at 11:11

For me, I was looking for months without prefixing with 0 if single digit. And I used this ([1-9]|(1[0-2])) and it works.

– bunjeeb
Feb 18 '17 at 0:39

Important to note: If you find this page wanting a solution for your number range that only has single digits before getting to the tens, 0[1-9]|1[0-2] won't work. Changing it to the logical next step [1-9]|1[0-2] doesn't work either for understandable reasons (It matches the 1 only in 10, 11, and 12). Had to use b(?:[0-9]|1[0-1])b to prevent that. b's makes sure regex matches word (or in this case number) boundaries (^ & $ didn't); brackets make the or (|) consider the other side of it; and finally ?: is to not create a submatch with the use of the brackets.

– user66001
Apr 13 '17 at 19:05

@polygenelubricants : "1,2,3,4,5,6,7,8,9,10,17,18".match(/^(([1-9]|1[0-7]),?)+$/g ) Can you please tell me why is this JS regex matches above 17?

– edam
Jan 24 '18 at 13:39

@edam - polygenelubricants could, and so could I, but then we'd be answering a questi… wait… is this a question you are asking in a comment? There are rulez on this site ;) Ask a Question if you have a new question. Comments are only for critiquing and asking for clarification, and for responding to those.

– robinCTS
Mar 9 '18 at 4:42

@edam Oh, I see. You did re-ask it as a question an hour later. That's great! However, it would probably be a good idea to delete your comment here.

– robinCTS
Mar 13 '18 at 11:11

add a comment |

Your pattern, [01-12] is thus broken down as follows:

0 - match the single digit 0

or, 1-1, match a single digit in the range of 1 through 1

or, 2, match a single digit 2

So basically all you're matching is 0, 1 or 2.

In order to do the matching you want, matching two digits, ranging from 01-12 as numbers, you need to think about how they will look as text.

You have:

01-09 (ie. first digit is 0, second digit is 1-9)

10-12 (ie. first digit is 1, second digit is 0-2)

You will then have to write a regular expression for that, which can look like this:

  +-- a 0 followed by 1-9

  |

  |      +-- a 1 followed by 0-2

  |      |

<-+--> <-+-->

0[1-9]|1[0-2]

      ^

      |

      +-- vertical bar, this roughly means "OR" in this context

Note that trying to combine them in order to get a shorter expression will fail, by giving false positive matches for invalid input.

For instance, the pattern [0-1][0-9] would basically match the numbers 00-19, which is a bit more than what you want.

answered Jun 30 '10 at 10:21

Lasse Vågsæther Karlsen

289k83521719

add a comment |

Your pattern, [01-12] is thus broken down as follows:

0 - match the single digit 0

or, 1-1, match a single digit in the range of 1 through 1

or, 2, match a single digit 2

So basically all you're matching is 0, 1 or 2.

In order to do the matching you want, matching two digits, ranging from 01-12 as numbers, you need to think about how they will look as text.

You have:

01-09 (ie. first digit is 0, second digit is 1-9)

10-12 (ie. first digit is 1, second digit is 0-2)

You will then have to write a regular expression for that, which can look like this:

  +-- a 0 followed by 1-9

  |

  |      +-- a 1 followed by 0-2

  |      |

<-+--> <-+-->

0[1-9]|1[0-2]

      ^

      |

      +-- vertical bar, this roughly means "OR" in this context

Note that trying to combine them in order to get a shorter expression will fail, by giving false positive matches for invalid input.

For instance, the pattern [0-1][0-9] would basically match the numbers 00-19, which is a bit more than what you want.

answered Jun 30 '10 at 10:21

Lasse Vågsæther Karlsen

289k83521719

add a comment |

Your pattern, [01-12] is thus broken down as follows:

0 - match the single digit 0

or, 1-1, match a single digit in the range of 1 through 1

or, 2, match a single digit 2

So basically all you're matching is 0, 1 or 2.

In order to do the matching you want, matching two digits, ranging from 01-12 as numbers, you need to think about how they will look as text.

You have:

01-09 (ie. first digit is 0, second digit is 1-9)

10-12 (ie. first digit is 1, second digit is 0-2)

You will then have to write a regular expression for that, which can look like this:

  +-- a 0 followed by 1-9

  |

  |      +-- a 1 followed by 0-2

  |      |

<-+--> <-+-->

0[1-9]|1[0-2]

      ^

      |

      +-- vertical bar, this roughly means "OR" in this context

Note that trying to combine them in order to get a shorter expression will fail, by giving false positive matches for invalid input.

For instance, the pattern [0-1][0-9] would basically match the numbers 00-19, which is a bit more than what you want.

answered Jun 30 '10 at 10:21

Lasse Vågsæther Karlsen

289k83521719

Your pattern, [01-12] is thus broken down as follows:

0 - match the single digit 0

or, 1-1, match a single digit in the range of 1 through 1

or, 2, match a single digit 2

So basically all you're matching is 0, 1 or 2.

In order to do the matching you want, matching two digits, ranging from 01-12 as numbers, you need to think about how they will look as text.

You have:

01-09 (ie. first digit is 0, second digit is 1-9)

10-12 (ie. first digit is 1, second digit is 0-2)

You will then have to write a regular expression for that, which can look like this:

  +-- a 0 followed by 1-9

  |

  |      +-- a 1 followed by 0-2

  |      |

<-+--> <-+-->

0[1-9]|1[0-2]

      ^

      |

      +-- vertical bar, this roughly means "OR" in this context

Note that trying to combine them in order to get a shorter expression will fail, by giving false positive matches for invalid input.

For instance, the pattern [0-1][0-9] would basically match the numbers 00-19, which is a bit more than what you want.

answered Jun 30 '10 at 10:21

Lasse Vågsæther Karlsen

289k83521719

answered Jun 30 '10 at 10:21

Lasse Vågsæther Karlsen

289k83521719

answered Jun 30 '10 at 10:21

Lasse Vågsæther Karlsen

289k83521719

answered Jun 30 '10 at 10:21

Lasse Vågsæther Karlsen

289k83521719

add a comment |

This also works:

^([1-9]|[0-1][0-2])$

[1-9] matches single digits between 1 and 9

[0-1][0-2] matches double digits between 10 and 12

There are some good examples here

answered Jun 30 '10 at 10:27

codingbadger

32.9k107997

2

To be exact, [0-1][0-2] also matches 00. That said, +1 for the link (which I've used in my answer).

– polygenelubricants
Jun 30 '10 at 11:05

1

[0-1][0-2] must be carefully interpreted, as it allows strings like 00, 01, and 02, but it doesn't admit 03 up to 09, admitting finally 10, 11 and 12. A right regex for that is [1-9]|1[0-2], or even 0*([1-9]|1[0-2]) (this last allowing any number of leading zeros).

– Luis Colorado
Sep 23 '15 at 20:50

add a comment |

This also works:

^([1-9]|[0-1][0-2])$

[1-9] matches single digits between 1 and 9

[0-1][0-2] matches double digits between 10 and 12

There are some good examples here

answered Jun 30 '10 at 10:27

codingbadger

32.9k107997

2

To be exact, [0-1][0-2] also matches 00. That said, +1 for the link (which I've used in my answer).

– polygenelubricants
Jun 30 '10 at 11:05

1

[0-1][0-2] must be carefully interpreted, as it allows strings like 00, 01, and 02, but it doesn't admit 03 up to 09, admitting finally 10, 11 and 12. A right regex for that is [1-9]|1[0-2], or even 0*([1-9]|1[0-2]) (this last allowing any number of leading zeros).

– Luis Colorado
Sep 23 '15 at 20:50

add a comment |

This also works:

^([1-9]|[0-1][0-2])$

[1-9] matches single digits between 1 and 9

[0-1][0-2] matches double digits between 10 and 12

There are some good examples here

answered Jun 30 '10 at 10:27

codingbadger

32.9k107997

This also works:

^([1-9]|[0-1][0-2])$

[1-9] matches single digits between 1 and 9

[0-1][0-2] matches double digits between 10 and 12

There are some good examples here

answered Jun 30 '10 at 10:27

codingbadger

32.9k107997

answered Jun 30 '10 at 10:27

codingbadger

32.9k107997

answered Jun 30 '10 at 10:27

codingbadger

32.9k107997

answered Jun 30 '10 at 10:27

codingbadger

32.9k107997

2

To be exact, [0-1][0-2] also matches 00. That said, +1 for the link (which I've used in my answer).

– polygenelubricants
Jun 30 '10 at 11:05

1

[0-1][0-2] must be carefully interpreted, as it allows strings like 00, 01, and 02, but it doesn't admit 03 up to 09, admitting finally 10, 11 and 12. A right regex for that is [1-9]|1[0-2], or even 0*([1-9]|1[0-2]) (this last allowing any number of leading zeros).

– Luis Colorado
Sep 23 '15 at 20:50

add a comment |

2

To be exact, [0-1][0-2] also matches 00. That said, +1 for the link (which I've used in my answer).

– polygenelubricants
Jun 30 '10 at 11:05

1

[0-1][0-2] must be carefully interpreted, as it allows strings like 00, 01, and 02, but it doesn't admit 03 up to 09, admitting finally 10, 11 and 12. A right regex for that is [1-9]|1[0-2], or even 0*([1-9]|1[0-2]) (this last allowing any number of leading zeros).

– Luis Colorado
Sep 23 '15 at 20:50

To be exact, [0-1][0-2] also matches 00. That said, +1 for the link (which I've used in my answer).

– polygenelubricants
Jun 30 '10 at 11:05

[0-1][0-2] must be carefully interpreted, as it allows strings like 00, 01, and 02, but it doesn't admit 03 up to 09, admitting finally 10, 11 and 12. A right regex for that is [1-9]|1[0-2], or even 0*([1-9]|1[0-2]) (this last allowing any number of leading zeros).

– Luis Colorado
Sep 23 '15 at 20:50

add a comment |

As polygenelubricants says yours would look for 0|1-1|2 rather than what you wish for, due to the fact that character classes (things in ) match characters rather than strings.

answered Jun 30 '10 at 10:17

fbstj

1,40411219

2

0|1-1|2 - this notation is very misleading. Something like 0|1|2 would be more accurate.

– polygenelubricants
Jun 30 '10 at 10:28

add a comment |

As polygenelubricants says yours would look for 0|1-1|2 rather than what you wish for, due to the fact that character classes (things in ) match characters rather than strings.

answered Jun 30 '10 at 10:17

fbstj

1,40411219

2

0|1-1|2 - this notation is very misleading. Something like 0|1|2 would be more accurate.

– polygenelubricants
Jun 30 '10 at 10:28

add a comment |

As polygenelubricants says yours would look for 0|1-1|2 rather than what you wish for, due to the fact that character classes (things in ) match characters rather than strings.

answered Jun 30 '10 at 10:17

fbstj

1,40411219

As polygenelubricants says yours would look for 0|1-1|2 rather than what you wish for, due to the fact that character classes (things in ) match characters rather than strings.

answered Jun 30 '10 at 10:17

fbstj

1,40411219

answered Jun 30 '10 at 10:17

fbstj

1,40411219

answered Jun 30 '10 at 10:17

fbstj

1,40411219

answered Jun 30 '10 at 10:17

fbstj

1,40411219

2

0|1-1|2 - this notation is very misleading. Something like 0|1|2 would be more accurate.

– polygenelubricants
Jun 30 '10 at 10:28

add a comment |

2

0|1-1|2 - this notation is very misleading. Something like 0|1|2 would be more accurate.

– polygenelubricants
Jun 30 '10 at 10:28

0|1-1|2 - this notation is very misleading. Something like 0|1|2 would be more accurate.

– polygenelubricants
Jun 30 '10 at 10:28

add a comment |

answered Jun 30 '10 at 10:20

Antal Spector-Zabusky

30.2k665127

add a comment |

answered Jun 30 '10 at 10:20

Antal Spector-Zabusky

30.2k665127

add a comment |

answered Jun 30 '10 at 10:20

Antal Spector-Zabusky

30.2k665127

answered Jun 30 '10 at 10:20

Antal Spector-Zabusky

30.2k665127

answered Jun 30 '10 at 10:20

Antal Spector-Zabusky

30.2k665127

answered Jun 30 '10 at 10:20

Antal Spector-Zabusky

30.2k665127

answered Jun 30 '10 at 10:20

Antal Spector-Zabusky

30.2k665127

add a comment |

Use this:

0?[1-9]|1[012]

07: valid

7: valid

0: not match

00 : not match

13 : not match

21 : not match

To test a pattern as 07/2018 use this:

/^(0?[1-9]|1[012])/([2-9][0-9]{3})$/

(Date range between 01/2000 to 12/9999 )

edited Jul 7 '18 at 7:10

answered Jan 23 '18 at 7:24

Eolia

493

I've been trying to figure out how to do this but to get the third condition of only a 0 to pass.

– mkaatman
Jul 5 '18 at 19:59

add a comment |

Use this:

0?[1-9]|1[012]

07: valid

7: valid

0: not match

00 : not match

13 : not match

21 : not match

To test a pattern as 07/2018 use this:

/^(0?[1-9]|1[012])/([2-9][0-9]{3})$/

(Date range between 01/2000 to 12/9999 )

edited Jul 7 '18 at 7:10

answered Jan 23 '18 at 7:24

Eolia

493

I've been trying to figure out how to do this but to get the third condition of only a 0 to pass.

– mkaatman
Jul 5 '18 at 19:59

add a comment |

Use this:

0?[1-9]|1[012]

07: valid

7: valid

0: not match

00 : not match

13 : not match

21 : not match

To test a pattern as 07/2018 use this:

/^(0?[1-9]|1[012])/([2-9][0-9]{3})$/

(Date range between 01/2000 to 12/9999 )

edited Jul 7 '18 at 7:10

answered Jan 23 '18 at 7:24

Eolia

493

Use this:

0?[1-9]|1[012]

07: valid

7: valid

0: not match

00 : not match

13 : not match

21 : not match

To test a pattern as 07/2018 use this:

/^(0?[1-9]|1[012])/([2-9][0-9]{3})$/

(Date range between 01/2000 to 12/9999 )

edited Jul 7 '18 at 7:10

answered Jan 23 '18 at 7:24

Eolia

493

edited Jul 7 '18 at 7:10

answered Jan 23 '18 at 7:24

Eolia

493

answered Jan 23 '18 at 7:24

Eolia

493

answered Jan 23 '18 at 7:24

Eolia

493

I've been trying to figure out how to do this but to get the third condition of only a 0 to pass.

– mkaatman
Jul 5 '18 at 19:59

add a comment |

I've been trying to figure out how to do this but to get the third condition of only a 0 to pass.

– mkaatman
Jul 5 '18 at 19:59

I've been trying to figure out how to do this but to get the third condition of only a 0 to pass.

– mkaatman
Jul 5 '18 at 19:59

add a comment |

-3

To solve this you can use /^[0-1][0-9]$/;
And if you want only 01 to 12, you need to check two conditions:

Whether the value is 00 using if statement:

if(thevale=="00")

{

    // message to user...not allowed

}

and:

if(thevalue >=13)

{

    // message to user...not allowed

}

Sample code in Javascript:

function CheckMonth(txtBox) {        

        var ex = /^[0-1][0-9]$/;

        if (txtBox.value.trim() != "") {

            if (txtBox.value.trim() == "00") {

                alert('Please enter valid numbers.');

                txtBox.value = "";

                txtBox.focus();

            }

            else if (ex.test(txtBox.value.trim()) == false) {

                alert('Please enter valid numbers.');

                txtBox.value = "";

                txtBox.focus();

            }

            else if (parseInt(txtBox.value.trim()) >= 13) {

                alert('Please enter valid numbers.');

                txtBox.value = "";

                txtBox.focus();

            }

        }

    }

edited Oct 27 '14 at 11:32

the swine

7,35253581

answered Oct 27 '14 at 11:22

KGowda M V

1

The response doesn't address a solution with regexp as requested. Solution can be obtained with only regexp and no need of converting the strings to numbers to calculate.

– Luis Colorado
Sep 23 '15 at 20:57

add a comment |

-3

To solve this you can use /^[0-1][0-9]$/;
And if you want only 01 to 12, you need to check two conditions:

Whether the value is 00 using if statement:

if(thevale=="00")

{

    // message to user...not allowed

}

and:

if(thevalue >=13)

{

    // message to user...not allowed

}

Sample code in Javascript:

function CheckMonth(txtBox) {        

        var ex = /^[0-1][0-9]$/;

        if (txtBox.value.trim() != "") {

            if (txtBox.value.trim() == "00") {

                alert('Please enter valid numbers.');

                txtBox.value = "";

                txtBox.focus();

            }

            else if (ex.test(txtBox.value.trim()) == false) {

                alert('Please enter valid numbers.');

                txtBox.value = "";

                txtBox.focus();

            }

            else if (parseInt(txtBox.value.trim()) >= 13) {

                alert('Please enter valid numbers.');

                txtBox.value = "";

                txtBox.focus();

            }

        }

    }

edited Oct 27 '14 at 11:32

the swine

7,35253581

answered Oct 27 '14 at 11:22

KGowda M V

1

The response doesn't address a solution with regexp as requested. Solution can be obtained with only regexp and no need of converting the strings to numbers to calculate.

– Luis Colorado
Sep 23 '15 at 20:57

add a comment |

-3

To solve this you can use /^[0-1][0-9]$/;
And if you want only 01 to 12, you need to check two conditions:

Whether the value is 00 using if statement:

if(thevale=="00")

{

    // message to user...not allowed

}

and:

if(thevalue >=13)

{

    // message to user...not allowed

}

Sample code in Javascript:

function CheckMonth(txtBox) {        

        var ex = /^[0-1][0-9]$/;

        if (txtBox.value.trim() != "") {

            if (txtBox.value.trim() == "00") {

                alert('Please enter valid numbers.');

                txtBox.value = "";

                txtBox.focus();

            }

            else if (ex.test(txtBox.value.trim()) == false) {

                alert('Please enter valid numbers.');

                txtBox.value = "";

                txtBox.focus();

            }

            else if (parseInt(txtBox.value.trim()) >= 13) {

                alert('Please enter valid numbers.');

                txtBox.value = "";

                txtBox.focus();

            }

        }

    }

edited Oct 27 '14 at 11:32

the swine

7,35253581

answered Oct 27 '14 at 11:22

KGowda M V

To solve this you can use /^[0-1][0-9]$/;
And if you want only 01 to 12, you need to check two conditions:

Whether the value is 00 using if statement:

if(thevale=="00")

{

    // message to user...not allowed

}

and:

if(thevalue >=13)

{

    // message to user...not allowed

}

Sample code in Javascript:

function CheckMonth(txtBox) {        

        var ex = /^[0-1][0-9]$/;

        if (txtBox.value.trim() != "") {

            if (txtBox.value.trim() == "00") {

                alert('Please enter valid numbers.');

                txtBox.value = "";

                txtBox.focus();

            }

            else if (ex.test(txtBox.value.trim()) == false) {

                alert('Please enter valid numbers.');

                txtBox.value = "";

                txtBox.focus();

            }

            else if (parseInt(txtBox.value.trim()) >= 13) {

                alert('Please enter valid numbers.');

                txtBox.value = "";

                txtBox.focus();

            }

        }

    }

edited Oct 27 '14 at 11:32

the swine

7,35253581

answered Oct 27 '14 at 11:22

KGowda M V

edited Oct 27 '14 at 11:32

the swine

7,35253581

edited Oct 27 '14 at 11:32

the swine

7,35253581

edited Oct 27 '14 at 11:32

the swine

7,35253581

answered Oct 27 '14 at 11:22

KGowda M V

answered Oct 27 '14 at 11:22

KGowda M V

answered Oct 27 '14 at 11:22

KGowda M V

1

The response doesn't address a solution with regexp as requested. Solution can be obtained with only regexp and no need of converting the strings to numbers to calculate.

– Luis Colorado
Sep 23 '15 at 20:57

add a comment |

1

The response doesn't address a solution with regexp as requested. Solution can be obtained with only regexp and no need of converting the strings to numbers to calculate.

– Luis Colorado
Sep 23 '15 at 20:57

The response doesn't address a solution with regexp as requested. Solution can be obtained with only regexp and no need of converting the strings to numbers to calculate.

– Luis Colorado
Sep 23 '15 at 20:57

add a comment |

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