Created by CyanHall.com
on 11/12/2020
, Last updated: 03/30/2021.
πΒ Β
Star me if itβs helpful.
πΒ Β
1. Hello
// hello.go The program entry main function must be in a code package named main.
package main
import (
"fmt"
)
func main() {
str := "world"
text := fmt.Sprintf("hello %s! happy coding.", str)
fmt.Println(text)
}
3. init
package main
import "fmt"
func init() {
fmt.Println("init 1")
}
func main() {
fmt.Println("main")
}
func init() {
fmt.Println("init 2")
}
// init 1
// init 2
// main
5. JSON
type Config struct {
Name bool `json:"name"` // OK
Name bool `json: "name"` // Error
Name bool `json:name` // Error
}
7. Array
var number_array [3]int // [0, 0, 0]
append(number_array, 1) // Error
number_array[0] = 1 // [1, 0, 0]
9. Map
your_map := make(map[string]int)
your_map["key"] = 1
fmt.Println(your_map["key"]) // 1
// Remove key
delete(elements, "key")
11. Interface
// res.Data is <interface {}>, res.Data > data is <[]interface {}>
items = res.Data.([]interface{})
for i, item := range response {
data := item.(map[string]interface{})
data["id"].(float64)
}
13. Inside Debugger
# Set breakpoint
break [path/filename].go:[line_num]
# Run and should pauses at the breakpoint
continue
# Print variable
print [variable_name]
# Move to next line in the source
next
2. env
go -h
go env
// run
go run hello.go
go build hello.go; ./hello
4. import
import format "fmt" // format.Println()
import "fmt" // fmt.Println()
import . "fmt" // use Println directly, not recommended
import _ "net/http/pprof" // used to load pprof package, it's init function will be called.
6. String
import (
"strings"
)
strings.Contains("something", "some") // true
8. Slice
var number_slice []int // []
// Recreate to append
number_slice = append(number_slice, 1) // [1]
// Create a new slice from an array
some_numbers := number_array[0:1] // [0]
10. Loop
names := []string{"a", "b", "c"} // [a b c]
for i, name := range names {
fmt.Printf("%d. %s
", i+1, name)
}
// 1. a
// 2. b
// 3. c
12. Debug using Delve
# https://github.com/go-delve/delve
dlv debug app.go
14. Gin
// Read Request Body in JSON
type GitHubInput struct {
Zen string `json:"zen"`
}
var input GitHubInput
if err := c.ShouldBindJSON(&input); err != nil {
c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
return
}
input.Zen
// Read Header
c.Request.Header.Get("X-GitHub-Event")
// HTTP Response
c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
c.String(200, input.Zen)
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