introduction to go language programming
TRANSCRIPT
Introduction to go languageprogramming
Mahmoud masih tehraniClickyab
Spring 2016
Golang history
Robert Griesemer, Rob Pike and Ken Thompson started sketching the goals for a new language on the white board on September 21, 2007. Within a few days the goals had settled into a plan to do something and a fair idea of what it would be. Design continued part-time in parallel with unrelated work. By January 2008, Ken had started work on a compiler with which to explore ideas; it generated C code as its output. By mid-year the language had become a full-time project and had settled enough to attempt a production compiler. In May 2008, Ian Taylor independently started on a GCC front end for Go using the draft specification. Russ Cox joined in late 2008 and helped move the language and libraries from prototype to reality.
Go became a public open source project on November 10, 2009. Many people from the community have contributed ideas, discussions, and code.
Go is multiplatformGoogle's Go compiler, "gc", is developed as open source software and targets various platforms including Linux, OS X, Windows, various BSD and Unix versions, and since 2015 also mobile devices, including smartphones. A second compiler, gccgo, is a GCC frontend.The "gc" toolchain is self-hosting since version 1.5
Why go?Go is easier to write (correctly) than C.
Go is easier to debug than C (even absent a debugger).
Go is the only language you'd need to know; encourages contributions.
Go has better modularity, tooling, testing, profiling, ...
Go makes parallel execution trivial.
Benchmark with go,ruby,python,node,php
https://www.techempower.com/benchmarks
How install go and use that!?Install : sudo apt-get install golang
Show version : go version
>>go version go1.6.1 linux/amd64
Show help : go help
Run code : go run YOUR_PACKAGE_NAME.go
Compile code : go install YOUR_PACKAGE_NAME.go
Which IDE for go● Sublime Text 2
● IntelliJ
● LiteIDE
● Netbeans
● Eclipse
● TextMate
● Komodo
● vim
● Emacs
Getting start to learn gopackage main
import ("fmt")
func main() {
fmt.Println("Hello, محمود")
}
Comment// comments in which all the
text between the // and the end of the line is part of
the comment and /* */ comments where everything
between the * s is part of the comment. (And may in-
clude multiple lines)
Install packages
1. Download and install it:
$ go get github.com/gin-gonic/gin
2. Import it in your code:
import "github.com/gin-gonic/gin"
Types in goInteger:
uint8 , uint16 , uint32 , uint64 ,
int8 , int16 , int32 and int64
Floating point:
float32 and float64
String:
string
operators+ addition
- subtraction
* multiplication
/ division
% remainder
stringsString literals can be created using double quotes
"Hello World" or back ticks `Hello World` . The differ-
ence between these is that double quoted strings can-
not contain newlines and they allow special escape se-
quences. For example \n gets replaced with a newline
and \t gets replaced with a tab character.
stringspackage main
import "fmt"
func main() {
fmt.Println(len("Hello World"))
fmt.Println("Hello World"[1])
fmt.Println("Hello " + "World")
}
Booleans&& and
|| or
! not
Booleansfunc main() {
fmt.Println(true && true)
fmt.Println(true && false)
fmt.Println(true || true)
fmt.Println(true || false)
fmt.Println(!true)
}
Booleans$ go run main.go
true
false
true
true
false
variablespackage main
import "fmt"
func main() {
var x string = "Hello World"
fmt.Println(x)
}
variablespackage main
import "fmt"
func main() {
var x string
x = "Hello World"
fmt.Println(x)
}
variablespackage main
import "fmt"
func main() {
var x string
x = "first"
fmt.Println(x)
x = "second"
fmt.Println(x)}
variablesvar x string
x = "first "
fmt.Println(x)
x = x + "second"
fmt.Println(x)
variablesvar x string = "hello"
var y string = "world"
fmt.Println(x == y)
>>false
variablesX := "Hello World"
Naming variablesname := "Max"
fmt.Println("My dog's name is", name)
dogsName := "Max"
fmt.Println("My dog's name is", dogsName)
scopepackage main
import "fmt"
func main() {
var x string = "Hello World"
fmt.Println(x)
}
scopevar x string = "Hello World"
func main() {
fmt.Println(x)
}
func f() {
fmt.Println(x)
}
scopefunc main() {
var x string = "Hello World"
fmt.Println(x)
}
func f() {
fmt.Println(x)
}
Constantspackage main
import "fmt"
func main() {
const x string = "Hello World"
fmt.Println(x)
}
Constantsconst x string = "Hello World"
x = "Some other string"
>>.\main.go:7: cannot assign to x
Defining Multiple Variablesvar (
a = 5
b = 10
c = 15
)
An Example Programpackage main
import "fmt"
func main() {
fmt.Print("Enter a number: ")
var input float64
fmt.Scanf("%f", &input)
output := input * 2
fmt.Println(output)
}
Forpackage main
import "fmt"
func main() {
i := 1
for i <= 10 {
fmt.Println(i)
i = i + 1
}
}
Forfunc main() {
for i := 1; i <= 10; i++ {
fmt.Println(i)
}
}
If1 odd
2 even
3 odd
4 even
5 odd
6 even
7 odd
8 even
9 odd
10 even
Iffunc main() {
for i := 1; i <= 10; i++ {
if i % 2 == 0 {
fmt.Println(i, "even")
} else {
fmt.Println(i, "odd")
}
}
}
switchswitch i {
case 0: fmt.Println("Zero")
case 1: fmt.Println("One")
case 2: fmt.Println("Two")
case 3: fmt.Println("Three")
default: fmt.Println("Unknown Number")
}
Arraypackage main
import "fmt"
func main() {
var x [5]int
x[4] = 100
fmt.Println(x)
}
>>[0 0 0 0 100]
Arrayvar total float64 = 0
for i := 0; i < len(x); i++ {
total += x[i]
}
fmt.Println(total / len(x))
>># command-line-arguments
.\tmp.go:19: invalid operation: total / 5 (mismatched types float64 and int)
Arrayfmt.Println(total / float64(len(x)))
Arrayx := [5]float64{ 98, 93, 77, 82, 83 }
Slicefunc main() {
slice1 := []int{1,2,3}
slice2 := append(slice1, 4, 5)
fmt.Println(slice1, slice2)
}
mapsvar x map[string]int
x["key"] = 10
fmt.Println(x)
elements := map[string]string{
"H": "Hydrogen",
"He": "Helium",
"Li": "Lithium",
"Be": "Beryllium",
"B": "Boron",
"C": "Carbon",
}
mapselements := map[string]map[string]string{
"H": map[string]string{
"name":"Hydrogen",
"state":"gas",
},
"He": map[string]string{
"name":"Helium",
"state":"gas",
},}
mapsif el, ok := elements["He"]; ok {
fmt.Println(el["name"], el["state"])
}
functionfunc average(xs []float64) float64 {
total := 0.0
for _, v := range xs {
total += v
}
return total / float64(len(xs))
}
functionfunc main() {
xs := []float64{98,93,77,82,83}
fmt.Println(average(xs))
}
functionfunc f() (int, int) {
return 5, 6
}
func main() {
x, y := f()
}
func add(args ...int) int {
total := 0
for _, v := range args {
total += v
}
return total}
func main() {
fmt.Println(add(1,2,3))
}
Closurefunc main() {
add := func(x, y int) int {
return x + y
}
fmt.Println(add(1,1))
}
deferpackage main
import "fmt"
func first() {fmt.Println("1st")}
func second() {fmt.Println("2nd")}
func main() {defer second()
first()
}
deferf, _ := os.Open(filename)
defer f.Close()
panicpackage main
import "fmt"
func main() {
panic("PANIC")
str := recover()
fmt.Println(str)
}
referenceWikipedia.com
Golang.com
An Introduction to Programming in Go (go book) Caleb Doxsey