Go Getting started with Go
Remarks
Go is an open-source, compiled, statically typed language in the tradition of Algol and C. It boasts features such as garbage collection, limited structural typing, memory safety features, and easy-to-use CSP-style concurrent programming.
Versions
The latest major version release is in bold below. Full release history can be found here.
| Version | Release Date |
|---|---|
| 1.8.3 | 2017-05-24 |
| 1.8.0 | 2017-02-16 |
| 1.7.0 | 2016-08-15 |
| 1.6.0 | 2016-02-17 |
| 1.5.0 | 2015-08-19 |
| 1.4.0 | 2014-12-04 |
| 1.3.0 | 2014-06-18 |
| 1.2.0 | 2013-12-01 |
| 1.1.0 | 2013-05-13 |
| 1.0.0 | 2012-03-28 |
Setting up the environment
If Go is not pre-installed in your system you can go to https://golang.org/dl/ and choose your platform to download and install Go.
To set up a basic Go development environment, only a few of the many environment variables that affect the behavior of the go tool (See: Listing Go Environment Variables for a full list) need to be set (generally in your shell's ~/.profile file, or equivalent on Unix-like OSs).
GOPATH
Like the system PATH environment variable, Go path is a : (; on Windows) delimited list of directories where Go will look for packages. The go get tool will also download packages to the first directory in this list.
The GOPATH is where Go will setup associated bin , pkg , and src folders needed for the workspace:
src— location of source files:.go,.c,.g,.spkg— has compiled.afilesbin— contains executable files built by Go
From Go 1.8 onwards, the GOPATH environment variable will have a default value if it is unset. It defaults to $HOME/go on Unix/Linux and %USERPROFILE%/go on Windows.
Some tools assume that GOPATH will contain a single directory.
GOBIN
The bin directory where go install and go get will place binaries after building main packages. Generally this is set to somewhere on the system PATH so that installed binaries can be run and discovered easily.
GOROOT
This is the location of your Go installation. It is used to find the standard libraries. It is very rare to have to set this variable as Go embeds the build path into the toolchain. Setting GOROOT is needed if the installation directory differs from the build directory (or the value set when building).
Accessing Documentation Offline
For full documentation, run the command:
godoc -http=:<port-number>
For a tour of Go (highly recommended for beginners in the language):
go tool tour
The two commands above will start web-servers with documentation similar to what is found online here and here respectively.
For quick reference check from command-line, eg for fmt.Print:
godoc cmd/fmt Print
# or
go doc fmt Print
General help is also available from command-line:
go help [command]
FizzBuzz
Another example of "Hello World" style programs is FizzBuzz. This is one example of a FizzBuzz implementation. Very idiomatic Go in play here.
package main
// Simple fizzbuzz implementation
import "fmt"
func main() {
for i := 1; i <= 100; i++ {
s := ""
if i % 3 == 0 {
s += "Fizz"
}
if i % 5 == 0 {
s += "Buzz"
}
if s != "" {
fmt.Println(s)
} else {
fmt.Println(i)
}
}
}
Hello, World!
Place the following code into a file name hello.go :
package main
import "fmt"
func main() {
fmt.Println("Hello, 世界")
}
When Go is installed correctly this program can be compiled and run like this:
go run hello.go
Output:
Hello, 世界
Once you are happy with the code it can be compiled to an executable by running:
go build hello.go
This will create an executable file appropriate for your operating system in the current directory, which you can then run with the following command:
Linux, OSX, and other Unix-like systems
./hello
Windows
hello.exe
Note: The Chinese characters are important because they demonstrate that Go strings are stored as read-only slices of bytes.
Listing Go Environment Variables
Environment variables that affect the go tool can be viewed via the go env [var ...] command:
$ go env
GOARCH="amd64"
GOBIN="/home/yourname/bin"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/yourname"
GORACE=""
GOROOT="/usr/lib/go"
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build059426571=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
By default it prints the list as a shell script; however, if one or more variable names are given as arguments, it prints the value of each named variable.
$go env GOOS GOPATH
linux
/home/yourname
Running Go online
The Go Playground
One little known Go tool is The Go Playground. If one wants to experiment with Go without downloading it, they can easily do so simply by . . .
- Visiting the Playground in their web browser
- Entering their code
- Clicking “Run”
Sharing your code
The Go Playground also has tools for sharing; if a user presses the “Share” button, a link (like this one) will be generated that can be sent to other people to test and edit.
In action
