preg_replace only first number in string

Question

First of all: I'm very bad with regular expressions, the ones I already have here I found on the net.

I want to increment the first number in a string, e.g. $teststring = "abcd1234efgh56";

I have already found the following:

preg_replace( "|(\d+)|e", "$1+1", $teststring);

will result in abcd1235efgh57

preg_replace( "|(\d+)(?!.*\d)|e", "$1+1", $teststring);

will result in abcd1234efgh57

but how do I increment ONLY the first number (1234 in the example) while leaving the rest of the string as is?

Thank you very much in advance

mgrueter · Accepted Answer · 2013-07-24 14:46:07Z

3

check out the docs: php.net manual on preg_replace

use the fourth parameter to limit the number of replaces

answered Jul 24, 2013 at 14:46

mgrueter

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Steven · Accepted Answer · 2013-07-24 15:30:08Z

0

You could use:

preg_replace('/([^0-9]*)(\d+)(.*)/e', '"$1" . ($2+2) . "$3"' , $str, 1);

This would match all non-numeric characters (if any) before the first number as $1, the first number as $2, and all following characters (if any) as $3.

It then outputs the string with 2 added to the first number (you can change $2+2 to $2+NUMBER).

The final parameter 1 in the function is limiting the repeats to 1 time only...

answered Jul 24, 2013 at 15:30

Steven

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Comments

Ronak Modi · Accepted Answer · 2013-10-12 19:03:46Z

0

The optional fourth parameter of preg_replace is limit :

preg_replace($search , $replace, $subject, $limit)

You can put 1 for your case..

it will give you

$teststring = 'abcd1235efgh56'

edited Oct 12, 2013 at 19:03

answered Jul 24, 2013 at 16:20

Ronak Modi

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MajorCaiger · Accepted Answer · 2013-07-24 14:47:51Z

-1

Try

preg_replace('/^([^0-9]+)?([0-9]+)([^0-9]+)?/', "$2+1", $teststring);

answered Jul 24, 2013 at 14:47

MajorCaiger

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4 Comments

Barmar Over a year ago

This will only work if there are exactly two numbers in the string.

MajorCaiger Over a year ago

Just tested it and it works with 1 or more numbers in the string

Barmar Over a year ago

Ahh, never mind. I was confused by the unnecessary [^0-9]+.

Barmar Over a year ago

I just tried it, the output was 1234+156. That's not even close to right.

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