2:go Basic Knowledge

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package mainimport  ("FMT") Func main ()  {c ()}// 1, Variable func test1 ()  {//--------- --------------------1.1 Variable declaration var v1 intvar v2 stringvar v3 [10]int //array var  v4 []int   //Array Slicing Var v5 struct {f int}var v6 *int            //Pointer var v7 map[string]int // Key is Mapvar v8 func (a int) with String  value int,  int//----------------------------- 1.2 Initialization of variables var v9 int = 10var v10 = 10v11 := 10//------------------- ----------1.3 Anonymous variable//When a function is called to return multiple values, and you only need to use a certain number of times, then the other variables with "_" instead of _, _, nickname := getname ()}// 1.3  Anonymous variable Supplement Func getname ()   (firstname, lastname, nickname string)  {return   "Michael",  "Ma",  "Liang"}//II: Constant Func test2 ()  {//-----------------------------2.1   Constant Const pi float64 = 3.14159265358979323846const zero = 0.0 //const  (size int64 =  1024eof        = -1 //) const u, v  float32 = 0, 3const a, b, c = 3, 4,  "foo"//----------------- ------------2.2  Reserved Constants//true false iota;iota are special, constants that the compiler can modify, reset to 0 at each const occurrence, and before the next const appears, Each occurrence of a iota will increment 1const  ( // iota is reset to 0c0 = iota // c0 == 0c1 = &NBSP;IOTA&NBSP;//&NBSP;C1&NBSP;==&NBSP;1C2&NBSP;=&NBSP;IOTA&NBSP;//&NBSP;C2&NBSP;==&NBSP;2) const  (A1  = 1 << iota // a == 1  (iota at each const beginning each reset to 0) b1 =  1 << iota // b == 2c3 = 1 << iota // c  == 4) const  (u1          = iota *  42 // u == 0v12 float64 = iota * 42 // v == 42.0w            = iota * 42 // w ==  const x = iota // x == 0  (because Iota is reset to 0 again) const y =  iota //y==0  Ibid.//-----------------------------2.3 Enumerate//Develop a series of related constants as follows const  (sunday =  Iotamondaytuesdaywednesdaythursdayfridaysaturdaynumberofdays)}//Three: Type Func test3 ()  {//---------------- -------------3.1: Base type//Boolean type: bool//integer: int8 byte int16 int uint uintptr//floating-point type: float32  float64//Complex Type: complex64 complex128//string: string//character type: rune//error type: error//---------------------------- -3.2: Composite type//pointer//array//slice//dictionary//channel//struct//interface}//Four: Process Control Func test4 ()  {//----------------------------- 4.1 Select Switch i {case 0:fmt. Printf ("0") case 1:fmt. Printf ("1") case 2:fallthroughcase 3:fmt. Printf ("3") Case 4, 5, 6:fmt. Printf ("4, 5, 6") default:fmt. Printf ("Default")}switch {case 0 <= num && num <= 3:fmt. Printf ("0-3") case 4 <= num && num <= 6:fmt. Printf ("4-6") case 7 <= num && num <= 9:fmt. Printf ("7-9")}//-----------------------------4.2 loop sum := 0for i := 0; i  < 10; i++ {sum += i}sum2 := 0for {sum2++if sum2 >  100 {break}}//-----------------------------4.3 jump//Roll your sister jump IT&NBSP;:=&NBSP;0HERE:FMT. Println (i) it++if i < 10 {goto here}//-----------------------------4.4-piece If a  < 5 {return 0} else {return 1}}//Five: function//----------------------------- 5.1 function definitions//func  functions name   (parameter list) return value {function Body    return statement}//case problem is not Func imafunc (a int, b  int)   (RET&NBSp;int, err error)  {if a < 0 | |  b < 0 {err = errors. New ("should be non-negative numbers!") return}return a + b, nil}//-----------------------------5.2 Function call Func a ()  {// This is how the Imafc, err := imafunc (1, 2) FMT is called. Println (imafc, err)}//-----------------------------5.3 Indeterminate parameter type Func myfunc (args ...int)  {for  _, arg := range args {fmt. Println (ARG)}}//calls Func b ()  {myfunc (1, 2, 3, 4, 5, 6, 7)}//------------ -----------------more than 5.4 return values//See Imafunc function//-----------------------------5.5 anonymous function//instance 1package mainimport  ( "FMT") Func main ()  {func (a, b int)   (sum int)  {sum = a +  Bfmt. PRINTLN (SUM) return} (1,&NBSP;2)//parentheses directly after the argument represents a direct call to the}//instance 2package mainimport  ("FMT") Func main ()   {Nm := func (a, b int)   (suM int)  {sum = a + bfmt. Println (sum) return}nm (1, 2)}//VI: Error handling Func foo (param int) (N int, err error)  { &NBSP, ...} The method is called as follows N, err := foo (0) if err != nil {//  error handling} else {//   Use return value}//seven: defer//-----------------------------7.1func copyfile (dst, src string)   (w  int64, err error)  {srcfile, err := os. Open (SRC)  if err != nil {return}defer srcfile.close () dstfile, err :=  os. Create (DstName) if err != nil {return}defer dstfile.close () Return io. Copy (dstfile, srcfile)}//-----------------------------7.2//panic () and Recover ()//I'm not done yet.