Basic syntax example for go

Examples of common Syntax

package main // Package name  mian A package represents a program that can be executed independently   The package name can be different from the directory name   One package per directory 
import (  
    "fmt"
    "os"
 )
 //init Special functions , Every package containing this function will execute this function first 
func init(){

}
// Main executive function 
func main() {
    fmt.Println("hello, world")
}
// Basic types  int、float、bool、string
// The compound type  struct ( Structure )、array、slice（ section ）、map、channel（ passageway ）
// Interface  interface
// function 
func add(n1 int,n2 int)(num int){
    num= n1+n2
    return n1+n2
}
const Pi = 3.14159 
var str string // The default value is  int  by  0,float  by  0.0,bool  by  false,string  Is an empty string , Pointer for  nil
type TZ int32 //TZ Express int32 Another name for 
time.Now() // current time 

if condition1 {
    // do something 
} else if condition2 {
    // do something else 
}else {
    // catch-all or default
}

switch var1 {
    case val1:
        ...
    case val2,val3,val4:
    case 0: //  Empty branch , Only when  i == 0  Only when you enter the branch 
    case 0: fallthrough // The code that takes the next branch 
        ...
    default:
        ...
}
for i := 0; i < 5; i++ {
    fmt.Printf("This is the %d iteration\n", i)
}
for pos, char := range str {
    ...
}
// Structure   With label 
type TagType struct { // tags
    field1 bool   "An important answer"
    field2 string "The name of the thing"
    field3 int    "How much there are"
}

Common methods

// character string 
-  character string  str  Of the  1  Bytes ：str[0] 
-  The first  i  Bytes ：str[i - 1] 
-  Last  1  Bytes ：str[len(str)-1] 
 Use the plus sign  +  Splicing strings is not the most efficient way , A better way is to use functions  strings.Join() 
strings  and  strconv  package  
HasPrefix  Judgment string  s  Whether or not to  prefix  start ： 
strings.HasPrefix(s, prefix string) bool 
Contains  Judgment string  s  Does it include  substr： 
strings.Contains(s, substr string) bool 
Index  Return string  str  In string  s  Index in （str  Index of the first character of ）,-1  Representation string  s  Does not contain a string  str： 
strings.Index(s, str string) int 
Replace  Used to string  str  In front of  n  A string  old  Replace with string  new, And return a new string , If  n = -1  Replace all strings  old  For the string  new： 
strings.Replace(str, old, new, n) string 
strings.ToLower(s) string // Replace with corresponding lowercase characters  
strings.TrimSpace(s)//  To eliminate the white space at the beginning and end of the string  
strings.Split(s, sep) Used to customize the split symbol to split the specified string , Also return to  slice. 
Join  Used to set the element type to  string  Of  slice  Use split symbols to splice together to form a string ： 
strings.Join(sl []string, sep string) string