65. Valid Number

Version #1 Go library

10.61 % 

import (
    "strconv"
    "strings"
)
func isNumber(s string) bool {
    _, err := strconv.ParseFloat(strings.TrimSpace(s), 64)
    return err == nil || strings.Contains(err.Error(), "value out of range")
}

[Go]Notes

Defer

A defer statement defers the execution of a function until the surrounding function returns.

The deferred call's arguments are evaluated immediately, but the function call is not executed until the surrounding function returns.

Closures

https://www.calhoun.io/5-useful-ways-to-use-closures-in-go/

[Go]Exercise: Loops and Functions

package main

import (
"fmt"
"math"
)

const Delta = 1e-10
func Sqrt(x float64) float64 {
i := 0
z := float64(1)
prev := z
for i < 10 {
z -= (z * z - x) / (2 * z)
fmt.Println(z)
if math.Abs(z - prev) < Delta {
break;
}
prev = z
i++
}
return z
}

func main() {
fmt.Println(Sqrt(2))
}

[Go]Methods are functions

Methods
A method is a function with a special receiver argument.

package main

import (
"fmt"
"math"
)

type Vertex struct {
X, Y float64
}

func (v Vertex) Abs() float64 {
return math.Sqrt(v.X*v.X + v.Y*v.Y)
}

func main() {
v := Vertex{3, 4}
fmt.Println(v.Abs())
}

------------------------------------------------------------------
Regular Function
package main

import (
"fmt"
"math"
)

type Vertex struct {
X, Y float64
}

func Abs(v Vertex) float64 {
return math.Sqrt(v.X*v.X + v.Y*v.Y)
}

func main() {
v := Vertex{3, 4}
fmt.Println(Abs(v))
}

[Go]Fibonacci closure

Version #2 "Go" Version

package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
prev := -1
curr := 1
return func() int {
prev, curr = curr, prev + curr
return curr
}
}

func main() {
f := fibonacci()
for i := 0; i < 10; i++ {
fmt.Println(f())
}
}

Version #1 "Java" Version
package main

import "fmt"

// fibonacci is a function that returns
// a function that returns an int.
func fibonacci() func() int {
prev := 0
curr := 1
return func() int {
next := prev + curr
prev = curr
curr = next
return prev
}
}

func main() {
f := fibonacci()
for i := 0; i < 10; i++ {
fmt.Println(f())
}
}