How can I simply validate whether a string is a valid IP in PHP?

Question

Using PHP, how do I validate that a string is a valid IP?

Examples of valid strings:

• 192.158.5.95
• 121.212
• 12.12.12.204

Answer 1

iNaD ist right, the filter_var() version is the best one - ip2long() is really not that failsave. Just try to put in some strange things and see for yourself. I did a performace-check and filter_var is pretty much faster than the common regex versions.