Template
This is all needed to test.
package main
func main() {
}
Variables
Semicolons are not needed.
var age int // assigned to 0 by default
var footSize = 45 // type inference
// multiple variables of same type
var headSize, waistSize = 200, 70
// constant declaration
const height = 180
var ( // multiple variables of different type
name = "Mario"
myAge = 5
lastName = "nope"
)
// shorthand declaration
heartSize, country := 100, "Italia"
// the space btw. variables is automatically given
fmt.Println("my age is:", age,
"and my foot size: ", footSize)
Functions
declaration
The basic structure for a Function is
func functionName(parameterName type) returnType {
// code
}
The parameters and the return type are optional. So the following is also valid go
func functionName() {
// code
}
For consecutive parameters with the same type, it is only needed to declare it once
// param1 is an int too
func functionName(param1, param2 int) {
}
Multiple return values
func functionName(param1, param2 int)(int, int) {
return param1, param2
}
func main() {
param1, param2 := functionName(12, 64)
}
Named, multiple return values
func functionName(param1, param2 int)(result1, result2 int) {
result1 = param1
result2 = param2
return // no explicit return value
}
blank identifier
_ is known as the blank identifier. It can be used in place of any value of any type to discard it.
// what happens if I only need result1 and want to discard result2?
func functionName(param1, param2 int)(result1, result2 int) {
result1 = param1
result2 = param2
return // no explicit return value
}
func main() {
param1, _ := functionName(12, 64)
}
Packages
Every go exec must have an entry point. This is a main function which has to reside in the main package.
We have the following tree:
src/
programm/
custom_package/
custom.go # custom class
programm.go # This is the main
To install the custom package from /src execute go install programm
To import the contents from custom.go and use it at programm.go we’ll have to import it with a relative path
package main
import (
"packages/custom"
)
func main() {
// code
}
Only the functions which start with a capital letter at custom.go will be exported and accessible from the outside.