regex for port number

matches a port number in computer networks

^((6553[0-5])|(655[0-2][0-9])|(65[0-4][0-9]{2})|(6[0-4][0-9]{3})|([1-5][0-9]{4})|([0-5]{0,5})|([0-9]{1,4}))$
gm
copy

Regex Flags

global match ?
ignore case ?
multiline ?
dotAll ?
unicode ?
sticky ?
hide matches
8080 3000 65535 65536

A port is a communication endpoint associated with a specific address

A port is a 16-bit unsigned integer ranging from 0 to 65535. The regex pattern tries to figure out if the input string falls under the given range.

A Better approach

Although this works, a far better(and simpler) approach would be this:

  1. Take the input string and convert it into a number
  2. If possible see if it falls in the range 0-65535
  3. If both the conditions succeed, then it is a valid port number

Cheatsheet

expr usage
/\w/ matches any word character (a-z, A-Z, 0-9, _)
/[0-9]/ matches all digits
/(hello){1,3}/ matches "hello" that occur between 1 and 3 times (inclusive)
/^/ matches beginning of a line
/$/ matches end of a line
view full cheatsheet
iHateRegex
by geon