How to filter or sanitize numbers from strings in PHP?

In this article, we discuss, how to extract or filter out numbers from a string in PHP.

There are various ways to do this, some prefer way we are discussing bellow

Table of content:

  1. Method 1: Using  filter_var() Function. 
  2. Method 2: Using  preg_replace() function.
  3. Method 3: Using preg_match_all() Function.
How to filter or sanitize numbers from strings in PHP?

Method 1: Using  filter_var() Function. 

The filter_var() function filters a variable with the specified filter and also sanitizes the data.

Syntax:

filter_var(var, filtername, options)

Return Value: It returns the filtered data on success, or FALSE on failure.

Example:

        
        <?php
$str = 'Welcome 2 bootstrapfriendly 2020';

// Filter the Numbers from String
$int_var = (int)filter_var($str, FILTER_SANITIZE_NUMBER_INT);

// print output of function
echo "The numbers are:". $int_var;

?>
        
    

The output of the above code is: 22020

Method 2: Using  preg_replace() function.

The preg_replace() PHP function is an inbuilt function in PHP that is used to perform a regular expression for search and replace the content. where all matches of a pattern or list of patterns found in the input are replaced with substrings.

Syntax:

preg_replace($patterns, $replacements, $input, $limit, $count)

Return Value: This function returns an array if the input parameter is an array, otherwise it will return a string.

Example :
        
        <?php

  // Declare a variable
  $str = 'Welcome 2 bootstrapfriendly 123';

  // Filter the Numbers from String
  $int_var = preg_replace('/[^0-9]/', '', $str);

   // print output of function
   echo "The numbers are:". $int_var;

?>
        
    

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The output of the above code is: 2123

Method 3: Using preg_match_all() Function.

The  preg_match() function is used to search a specific string or extract numbers from a string. Usually, the search starts from the starting of the input string. The optional parameter offset is used to specify the position from where to start the search.

Return:

The preg_match() function returns where a match was found in a string.

Syntax:

int preg_match( $pattern, $input, $matches, $flags, $offset )

Example:

        
        <?php

// Declare a variable
$str = 'Welcome 2 bootstrapfriendly 123';

// Use preg_match_all() function to check match
preg_match_all('!\d+!', $str, $matches);

// print output of function
print_r($matches);

?>
        
    

The output of the above code is :

Array ( [0] => Array ( [0] => 2 [1] => 123 ) )

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