Go Language Learning Notes

This is a creation in Article, where the information may have evolved or changed.

The array, slice, and map in Go

1. Array
   Definition of an array

var arr [Ten]int//definition array arr, default initial values are0arr[0] =1Change the value of the first element of the array to1Arr: = [3]int{1,2,3} arr: = [...]int{1,2,3}//Note...That represents the size of the array by the compiler itself/* Multidimensional array */arr: = [3][2]int{{1,2},{2,3},{3,4}}//reasonable arr: = [...][2]int{{1,2},{2,3},{3,4}}//Reasonable/* arr: = [3][...]int{{1,2},{2,3},{3,4}} Error */

1. Slice
   is equivalent to a slice inside python, but there are differences. The slice in Go is a pointer to an array and is a reference type. This means that when a slice is assigned to another variable, two references point to the same array. If a function requires a slice parameter, modifications to the slice element in it are also reflected in the function call, similar to the pointer passing the underlying array.

10)    // 创建一个保存有十个元素的slice/* slice总是与一个固定长度的array成对出现，其影响slice的容量和长度*/arr := [...]int{1,2,3,4,5}s1 := a[2:4]     // 创建序号为2-3（不含4）的slices2 := a[:]        // 创建一个与arr等长的slices3 := s[:4]       //用slice 创建slice

Go keyword

Break

	default	func	Interface	Select
Case	Defer	Go	Map	struct
Chan	Else	Goto	Package	Switch
Const	Fallthrough	If	Range	Type
Continue	For	Import	Return	Var

Control structure

• If, else

/*  用法: 除了条件不需要括号 ，其它和C一样*/if condition{    //...if-elseif-else 结构if codition1{    //...}elseif codition2{    //...}else{    //...}

• For, continue, break

for init;condition;post{}         // 常规用法forcondition{}                    // 相当于C语言的whilefor{}                          // 死循环/* continue 和 break 的用法和C语言相似 */

• switch, default, Fallthrough

/ * Usage one * /Switch Exp{ CaseCONS1:EXP1     CaseCONS2:EXP2    //...     CaseCONSN:EXPN Default:exp_}/ * Usage two * /Switch{//switch does not have an expression, it executes the part of true in the case expression     CaseCOND1:EXP1    //...     CaseCONDN:EXPN}/ * Switch statement using the Fallthrough keyword * /Switchi{//If i==0, it does not match down to execute EXP1     Case 0: Case 1:EXP1   //EXP1 will not be executed}Switchi{//If i==0, it will execute EXP1     Case 0: Fallthrough Case 1:EXP1   //EXP1 will be executed}

• Map, Range
  The keyword map can be thought of as an array indexed by a string

salary: =map  [string  ]int  { "Jane"  :3000 ,  :2500 ,  "Marry"  :1800 , //the last comma must have } for  key, value: = range  salary{/* is a bit like a python dictionary */ FMT. Printf ( "%s\t%d\n" , key, value)}[output]>>>jane   Tony  2500  Marry  1800  delete  (Salary,  "Jane" ) //built-in function delete delete element "Jane"  

Built-in functions

Close	New	Panic	Complex
Delete	Make	Recover	Real
Len	Append	Print	Image
Cap	Copy	println

• Append, copy

/ * Append for appending slice * /S0: = []int{0,0}S1: =Append(S0,1)//Append element 2 to S0 end, S1 = = []int{0, 0, 1}S2: =Append(S1, 2, 3, 4)//Append multiple elementsS3: =Append(S2, S0 ...)//Append a slice, note the back three points/ * Copy for copying slice, returning the number of copied elements * /Arr: = [...]int{1,2,3,4,5,6,7}vars = Make([]int,5)//Create a type of []int, save 5 elements of sliceN: =Copy(S, arr[:])//n==5, the value within S is A[:5]

• close
  for channel communication, use it to close channel
• Delete
  for deleting instances in map
• cap, len
  Cap return tile capacity
  Len To return strings, slice, and arrays of length
• new, make
  New for various types of memory allocations
  make ([]t, Len, CAP) for memory allocations of built-in types
• panic, recover
  for exception handling mechanisms
• complex, Real, imag
  for complex numbers