PHP-正则表达式匹配这样的字符串：2012/018843/06？

Question

I do not know very much about regular expressions but would like to create a regex to validate a string like this: `2012/018843/06.

If it may help someone in the future, I would like to say that would be for a South African Company Registration Number.

If anyone would be kind enough to post a regex that can be processed via PHP and does match this, that would be great. If not, any links to "the basics" of creating regular expressions in this manner would be much appreciated!

Thanks.

EDIT:

I have tried this:

[0-9/]{14}

But it does not match the length exactly.

Answer 1

In it's simplest form:

preg_match("|^\d{4}/\d{6}/\d{2}$|", $input);

The \\d token matches any integer 0 - 9, the integer inside {} indicates how many repetition are allowed from the previous tokens, the / matches literal / since I'm using | as the regex delimiter.

The ^ token is to match from the beginning of the string, and $ to match the end of string, this way, things like aa2012/124521/11bb won't match (it would match otherwise if you take out the ^$ )

Answer 2

are the numerics fixed in length? then try

preg_match('#^\d{4}/\d{6}/\d{2}$#', $string)

syntax:

• \\d is an escape sequence which represents any decimal digit (0-9), this could also be represented by [0-9]
• {4} defines, that the last expression (in this case: a decimal digit) has to occur 4 times, using this expression avoids repeating the previous expression many times, so \\d{4} means \\d\\d\\d\\d
• ^ represents the beginning of the string and $ the end of the string, so this ensures, that there are no other chars in this string, so a string like abc2012/018843/06def would not match