The challenge#

Write an algorithm that will identify valid IPv4 addresses in dot-decimal format. IPs should be considered valid if they consist of four octets, with values between `` and `255`, inclusive.

Valid inputs examples:

``````1.2.3.4
123.45.67.89
``````

Invalid input examples:

``````1.2.3
1.2.3.4.5
123.456.78.90
123.045.067.089
``````

Notes:

• Leading zeros (e.g. `01.02.03.04`) are considered invalid
• Inputs are guaranteed to be a single string

The solution in Golang#

Option 1:

``````package solution
import "net"
func Is_valid_ip(ip string) bool {
if r := net.ParseIP(ip); r == nil {
return false
}
return true
}
``````

Option 2:

``````package solution
import "net"
func Is_valid_ip(ip string) bool {
return net.ParseIP(ip) != nil
}
``````

Option 3:

``````package solution
import "regexp"
func Is_valid_ip(ip string) bool {
re, _ := regexp.Compile(`^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\$`)
if re.MatchString(ip) {
return true
}
return false
}
``````

Test cases to validate our solution#

``````package solution_test

import (
. "github.com/onsi/ginkgo"
. "github.com/onsi/gomega"
)
var _ = Describe("Test Example", func() {
It("should test that 12.255.56.1 is correct", func() {
Expect(Is_valid_ip("12.255.56.1")).To(Equal(true))
})
})

var _ = Describe("Test Example", func() {
It("should test that '' is uncorrect", func() {
Expect(Is_valid_ip("")).To(Equal(false))
})
})

var _ = Describe("Test Example", func() {
It("should test that abc.def.ghi.jkl is uncorrect", func() {
Expect(Is_valid_ip("abc.def.ghi.jkl")).To(Equal(false))
})
})

var _ = Describe("Test Example", func() {
It("should test that 123.456.789.0 is uncorrect", func() {
Expect(Is_valid_ip("123.456.789.0")).To(Equal(false))
})
})

var _ = Describe("Test Example", func() {
It("should test that 12.34.56 is uncorrect", func() {
Expect(Is_valid_ip("12.34.56")).To(Equal(false))
})
})

var _ = Describe("Test Example", func() {
It("should test that 12.34.56 .1 is uncorrect", func() {
Expect(Is_valid_ip("12.34.56 .1")).To(Equal(false))
})
})

var _ = Describe("Test Example", func() {
It("should test that 12.34.56.-1 is uncorrect", func() {
Expect(Is_valid_ip("12.34.56.-1")).To(Equal(false))
})
})

var _ = Describe("Test Example", func() {
It("should test that 123.045.067.089 is uncorrect", func() {
Expect(Is_valid_ip("123.045.067.089")).To(Equal(false))
})
})

var _ = Describe("Test Example", func() {
It("should test that 127.1.1.0 is correct", func() {
Expect(Is_valid_ip("127.1.1.0")).To(Equal(true))
})
})

var _ = Describe("Test Example", func() {
It("should test that 0.0.0.0 is correct", func() {
Expect(Is_valid_ip("0.0.0.0")).To(Equal(true))
})
})

var _ = Describe("Test Example", func() {
It("should test that 0.34.82.53 is correct", func() {
Expect(Is_valid_ip("0.34.82.53")).To(Equal(true))
})
})

var _ = Describe("Test Example", func() {
It("should test that 192.168.1.300 is uncorrect", func() {
Expect(Is_valid_ip("192.168.1.300")).To(Equal(false))
})
})
``````