Extract Numbers From String in PHP

Using filter_var() method

We can use the filter_var() method which filters a variable based on supplied filter flag or ID. To extract numbers from the string variable, we can pass the FILTER_SANITIZE_NUMBER_INT id.

Let’s see an example using this method.

This approach isn’t efficient for certain use case, and simply returns the numbers present within the string together. For a more efficient, we can rely on regular expression.

Use preg_match_all() method

Use preg_match_all() method with /[0-9]+/ to extract numbers from String in PHP.

Here, output is array of matches, which can then be used to extract the numbers from the string.

We used the preg_match_all() function to search for the regular expression and extracted the numbers from the string.

We used regular expression in the form of a pattern /[0-9]+/ that matched the numbers in the string.

preg_match_all performs global regular expression match. It takes three arguments:
$pattern : The pattern to be searched
$subject: Input String
$matches:Array of all matches in the String.

Use preg_replace() method

We can achieve the same output as the filter_var method using regular expression where we replace all the characters that are not numbers with empty whitespace. The regular expression match value would be /[^0-9]/.

Let’s illustrate this approach on the same string as in the previous section.

preg_replace() performs global regular expression match. It takes three arguments:
$pattern : The pattern to be searched
$replacement: the string to replace with searched string
$subject: Input String