CODEWITHSUNDEEP
regexstringsubstring
user954912
user954912

Reputation: 243

using Regular Expressions in PHP to return part of a string

I'm trying to retrieve only the version number out of a string, but the strings aren't formatted in a specific. For example, the strings may be written in (but not limited to) any of the following formats

I need to create a php function that will return ONLY the version number (ex: "2.0.0" from each of these strings. Would using regular expressions be useful at all in this task? If so, what built in PCRE (perl compatible regular expressions) PHP functions should I make use of?

Please keep in mind I have very little understanding of regular expressions. Thanks!

Upvotes: 2

Views: 828

Answers (2)

Czarek Tomczak
Czarek Tomczak

Reputation: 20645

Try this:

function GetVersion($string)
{
    if (preg_match("#(\d+\.\d+(\.\d+)*)#", $string, $match)) {
        return $match[1];
    }
}

$test_strings = array(
    "Angry Birds v2.0.0",
    "Angry Birds 2.0.0",
    "v1.25",
    "Version: 1.3",
    " 2.0.1 ",
    "Dots4You v3.15"
);

foreach ($test_strings as $string) {
    printf("%s<br>", GetVersion($string));
}

RESULT:

2.0.0

2.0.0

1.25

1.3

2.0.1

3.15

@Tim Pietzcker:

Your code will fail when project's name alone will contain a digit, for example "Dots4You v3.15" will catch "4" as a version. Version should contain at least 2 digits and 1 dot.

Upvotes: 3

Tim Pietzcker
Tim Pietzcker

Reputation: 336128

This sounds like a job that regexes are well suited for.

For example:

if (preg_match('/\d+(?:\.\d+)*/', $subject, $regs)) {
    $result = $regs[0];
} else {
    $result = "";
}

Explanation:

\d+  # Match one or more digits
(?:  # Try to match...
 \.  # a dot
 \d+ # and one or more digits...
)*   # zero or more times.

This also matches single version numbers like "Acrobat Reader 9"; if you don't want that and require at least one dot, simply use a + instead of a *: /\d+(?:\.\d+)+/

Or, you could use a word boundary anchor to make sure the regex never matches within a word like "Dots4You": /\d+(?:\.\d+)*\b/

Upvotes: 2

Related Questions