Determine if a string is a valid IPv4 address. The standard form of such an address is a dotted quad or dotted decimal string. That is, 4 decimal numbers separated by periods, each number ranging from 0 to 255 The \d is double-scaped so that the slash gets passed on the regex.
#!/usr/local/bin/ruby# Determine if a string is a valid IPv4 address. The standard# form of such an address is a dotted quad or dotted decimal# string. That is, 4 decimal numbers separated by periods,# each number ranging from 0 to 255 The \d is double-scaped# so that the slash gets passed on the regex.
num = "(\\d|[01]?\\d\\d|2[0-4]\\d|25[0-5])"# defined as string
num = /(\d|[01]?\d\d|2[0-4]\d|25[0-5])/# defined as regex
pat = "^(#{num}\.){3}#{num}$"
ip_pat = Regexp.new(pat)
puts ip_pat.class
ipl = "127.0.0.1"
puts ipl.class# "=~" is a matching operator with respect to regular# expressions; it returns the position in a string where a# match was found, or nil if the pattern did not match.if /\w/ =~ "this"
puts "yes"else
puts "no"end