$re = '/(?:^|\b(?<!\.))(?:1?\d?\d|2[0-4]\d|25[0-5])(?:\.(?:1?\d?\d|2[0-4]\d|25[0-5])){3}(?=$|[^\w.])/m';
$str = 'My input string & constraints are as follows :
IPv4 Range : 0.0.0.0 to 255.255.255.255 55.123.99.988 256.1.1.1
IPv4 address may / may not be present in the string
Valid Examples : this is an ip & this is an ip 200.100.2.32
String may start with IPv4 address
Valid Examples :
200.100.2.32 is an ip | Output : [\'200.100.2.32\']
Invalid Examples :
200.100.2.32is an ip | Output : []
String may end with IPv4 address
Valid Examples : the ip is 200.100.2.32
Output : [\'200.100.2.32\']
Invalid Examples : the ip is200.100.2.32
Output : []
String may contain an IPv4 address in the middle, and if it does - there will a space before and after the IPv4 address.
Valid Examples : the ip is 200.100.2.32 and it is ipv4 | Output : [\'200.100.2.32\']
Valid Examples : the ip is 200.100.2.32and it is ipv4 | Output : []
Multiple IPs may be present in a single string
Valid Examples : 200.100.2.32 100.50.1.16 | Output : [\'200.100.2.32\', \'100.50.1.16\']
Invalid Examples : 200.100.2.32.100.50.1.16 | Output : []
10.151.0.0,8.8.8.8,127.0.0.1,10.51.0.0,10.151.1.0';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php