Revisions to Regular expression for alphanumeric and underscores

Add PHP syntax highlighting

edited Oct 28, 2023 at 22:29

5.8k
4
20
37

In computer science, an alphanumeric value often means the first character is not a number, but it is an alphabet or underscore. Thereafter the character can be 0-9, A-Z, a-z, or underscore (_).

Here is how you would do that:

Tested under PHP:

$regex = '/^[A-Za-z_][A-Za-z\d_]*$/'

$regex = '/^[A-Za-z_][A-Za-z\d_]*$/'

Or take

^[A-Za-z_][A-Za-z\d_]*$

and place it in your development language.

In computer science, an alphanumeric value often means the first character is not a number, but it is an alphabet or underscore. Thereafter the character can be 0-9, A-Z, a-z, or underscore (_).

Here is how you would do that:

Tested under PHP:

$regex = '/^[A-Za-z_][A-Za-z\d_]*$/'

Or take

^[A-Za-z_][A-Za-z\d_]*$

and place it in your development language.

In computer science, an alphanumeric value often means the first character is not a number, but it is an alphabet or underscore. Thereafter the character can be 0-9, A-Z, a-z, or underscore (_).

Here is how you would do that:

Tested under PHP:

$regex = '/^[A-Za-z_][A-Za-z\d_]*$/'

Or take

^[A-Za-z_][A-Za-z\d_]*$

and place it in your development language.

Active reading [<https://en.wikipedia.org/wiki/Computer_science> <https://en.wiktionary.org/wiki/alphanumeric#Adjective> <https://en.wikipedia.org/wiki/PHP>].

Source Link

edited Oct 17, 2022 at 20:00

Peter Mortensen

31.4k
22
110
134

In Computer Sciencecomputer science, an Alphanumericalphanumeric value often means the first character is not a number, but it is an alphabet or underscore. Thereafter the character can be 0-9, A-Z, a-z, or underscore (_).

Here is how you would do that:

Tested under phpPHP:

$regex = '/^[A-Za-z_][A-Za-z\d_]*$/'

orOr take this

^[A-Za-z_][A-Za-z\d_]*$

and place it in your development language.

In Computer Science, an Alphanumeric value often means the first character is not a number but is an alphabet or underscore. Thereafter the character can be 0-9, A-Z, a-z, or underscore (_).

Here is how you would do that:

Tested under php:

$regex = '/^[A-Za-z_][A-Za-z\d_]*$/'

or take this

^[A-Za-z_][A-Za-z\d_]*$

and place it in your development language.

In computer science, an alphanumeric value often means the first character is not a number, but it is an alphabet or underscore. Thereafter the character can be 0-9, A-Z, a-z, or underscore (_).

Here is how you would do that:

Tested under PHP:

$regex = '/^[A-Za-z_][A-Za-z\d_]*$/'

Or take

^[A-Za-z_][A-Za-z\d_]*$

and place it in your development language.

Removed arrogant remarks. Very good answer but needn't express an opinion.

Source Link

edit approved Sep 14, 2017 at 19:00

Lupus Ossorum

459
4
17

I take a correct cracked at it.

Remember inIn Computer Science, an Alphanumeric value often means the first character is not a number but is an alphabet or underscore. Thereafter the character can be 0-9, A-Z, a-z, or underscore (_). Tested

Here is how you would do that:

Tested under php:

$regex = '/^[A-Za-z_][A-Za-z\d_]*$/'

or take this

^[A-Za-z_][A-Za-z\d_]*$

and place it in your development language.

I take a correct cracked at it.

Remember in Computer Science, an Alphanumeric value means the first character is an alphabet or underscore. Thereafter the character can be 0-9, A-Z, a-z, or underscore (_). Tested under php:

$regex = '/^[A-Za-z_][A-Za-z\d_]*$/'

or take this

^[A-Za-z_][A-Za-z\d_]*$

and place it in your development language.

In Computer Science, an Alphanumeric value often means the first character is not a number but is an alphabet or underscore. Thereafter the character can be 0-9, A-Z, a-z, or underscore (_).

Here is how you would do that:

Tested under php: