Table of Contents
- Unreferenced package
- Define variables or constants all together
- Unnamed function
- Using an aliases for packages
- You must pass a bool value to if's condition expression
- iota
- Swapping values in a slice
- Use Pointer type for a receiver of a struct
- Convert a string into a slice of runes
- Exception handling
- String interpolation
- Convert strings into a slice
- Convert an array to a string
- To Lower/UpperCase
- Convert ints (or any data type) into strings
- More golang tips?
Unreferenced package
You can keep unused packages below without causing any error by adding _ to the packages.
import _"fmt"Define variables or constants all together
You can define multiple variables or constants all together like the code below.
var (
n = 1
s = "string"
)
const (
t = true
T = false
)Unnamed function
f := func(x, y int) int { return x + y }
f(3,5) //=> 8Using an aliases for packages
You can make an aliases for packages like the code below.
import (
f "fmt"
. "test" // You can omit the package name when you use anything from this package.
)
func main() {
f.Println("hello")
T // From test
}You must pass a bool value to if’s condition expression
the value of condition expression in a if statement has to be a bool type.
if(true) {} // ok
if(1){} // Causing a compiling error.iota
Go’s iota identifier is used in const declarations to simplify definitions of incrementing numbers.
const (
A = iota // A == 0
B = iota // B == 1
C = iota // C == 2
)You can start the number from 1 like the below.
const (
A = 1 + iota // A == 1
B // B == 2
C // C == 3
)Swapping values in a slice
You can swap values in a slice like the code below.
func main() {
var list = []int { 1, 2, 3 ,4,5}
list[0], list[1] = list[1], list[0] // Reverse the order on the right side.
fmt.Println(list) //=> [2 1 3 4 5]
}Use Pointer type for a receiver of a struct
If you use a normal value type for a receiver like the code below, it does not work the way you expect. For further information about this, check here.
type Point struct {
X int
Y int
}
func (p Point) set(x, y int) {
p.X = x
p.Y = y
}
func main() {
p := Point{}
p.set(1,2)
fmt.Println(p) //=> {0 0}
}You should you a pointer type for a receiver.
type Point struct {
X int
Y int
}
func (p *Point) set(x, y int) {
p.X = x
p.Y = y
}
func main(){
p := Point{}
p.set(1,2)
fmt.Println(p) //=> {1 2}
}Convert a string into a slice of runes
Converting a string to a slice of runes yields a slice whose elements are the Unicode code points of the string.
s := "abc日"
r := []rune(s)
fmt.Printf("%v\n", r)
fmt.Printf("%U\n", r)
// Output:
// [97 98 99 26085]
// [U+0061 U+0062 U+0063 U+65E5]Exception handling
package main
import (
"fmt"
"os"
)
func main() {
result, err := os.Open("/nonexistence.txt")
if err != nil {
fmt.Println("There was an error")
fmt.Println(err)
return
//=> There was an error
//=> open /nonexistence.txt: no such file or directory
}
fmt.Println(result)
}
String interpolation
// import format
import ( "fmt" )
date := fmt.Sprintf("%d-%d-%d", year, month, day)
time := fmt.Sprintf("%d:%d:%d", hour, minute, second)
datetime := fmt.Sprintf("%s,%s", date, time)Convert strings into a slice
Use strings.Split.
fmt.Printf("%#v\n", strings.Split("abc", "")) //=> []string{"t", "e", "s", "t"}Convert an array to a string
You can concatenate an array of strings using strings.Join.
package main
import (
"fmt"
"strings"
)
func main() {
str := []string { "Go", "Ruby"}
fmt.Println(strings.Join(str, "/")) //=> Go/Ruby
}To Lower/UpperCase
fmt.Println(strings.ToLower("STR")) //=> str
fmt.Println(strings.ToUpper("str")) ///=> STRConvert ints (or any data type) into strings
You should look to use packages like strconv or functions like fmt.Sprintf. For example, here is an example using strconv.Itoa to convert an integer into a string.
package main
import (
"fmt"
"strings"
"strconv"
)
func main() {
i := 123
array := []string { "A", "B" }
fmt.Println(strconv.Itoa(i)) //=> 123
fmt.Println(returnString(array)) //=> The array becomes a string. [A B]
}
func returnString(arr []string) string{
return fmt.Sprintf("The array becomes a string. %v", arr)
}More golang tips?
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