Question 41000 in PHP Question posted in
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How to get NUMBER in a string "constant-string-NUMBER-*"? – PHP

I’ve strings like constant-string-NUMBER-* where

  • constant-string- is a costant string (that I know and can use in the effort of getting the NUMBER) e.g. fix-str-
  • NUMBER is any natural number
  • -* can be any string

String-result examples:

fix-str-0
// result: 0

fix-str-0-another-str
// result: 0

fix-str-123
// result: 123

fix-str-456789
// result: 456789

fix-str-123456789-yet-another-str
// result: 1234567899

fix-str-999999-another-str-123
// result: 999999

I would like to extract the NUMBER from those strings in PHP so that I can associate this number to a variable e.g. $numberFromString = ?.

Any insight?

Tags:

3

Answers


  1. 0

    You can represent a string as an array of characters. Use the PHP substr() Function, where the second argument is the number from which your string is left.

    Example. Return "world" from the string:

    <?php
echo substr("Hello world",6);
?>

    Info from here: https://www.w3schools.com/php/func_string_substr.asp

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  2. 0

    Try this:

    fix-str-(d+)
    • fix-str- match this string.
    • (d+) followed by one or more digits, and save the number inside the first capturing group.

    EDIT

    From @user3783243, we can also use fix-str-Kd+, without the need of a capturing group.

    fix-str-Kd+
    • fix-str- match this string, then..
    • K reset the starting point of the reported match.
    • d+ then match one or more digits.

    See regex demo

    <?php 
$str ="fix-str-123456789-yet-another-str fix-str-234";

$pattern = "/fix-str-Kd+/";

preg_match($pattern, $str, $arr1); //Find only the first match.

echo "The first match: " . $arr1[0]; //Output: 123456789

echo "nnn";

preg_match_all($pattern, $str, $arr2); //Find all the matches.

echo "All the matches: " . implode(',', $arr2[0]); //Output: 123456789,234
?>
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  3. 0

    Based on your string examples, there are two possible ways. One way could use explode, then of course the other way could be with preg_match for regex. I’ll show both ways, only to show that regex is not always absolutely necessary.

    Using explode:

    $strings = [
'fix-str-0',
'fix-str-0-another-str',
'fix-str-123',
'fix-str-456789',
'fix-str-123456789-yet-another-str',
'fix-str-999999-another-str-123',
];

$match = [];
$matches = [];
foreach ($strings as $string) {
    $match = explode('-', $string);
    
    if (count($match) >= 3) {
        $matches[] = $match[2]; // Array offset 2 has the number
    }
}

foreach($matches as $found) {
    echo $found, PHP_EOL;
}

// Output:

0
0
123
456789
123456789
999999

    Using preg_match:

    $strings = [
'fix-str-0',
'fix-str-0-another-str',
'fix-str-123',
'fix-str-456789',
'fix-str-123456789-yet-another-str',
'fix-str-999999-another-str-123',
];

$match = [];
$matches = [];
foreach ($strings as $string) {
      // match 1 or more digits, store to $match
    preg_match('/(d+)/', $string, $match);
    
    if (!empty($match)) {
        $matches[] = $match[0]; // use the first match
    }
}

foreach($matches as $found) {
    echo $found, PHP_EOL;
}

// Output:

0
0
123
456789
123456789
999999
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