Go fast-04-constants, operators and pointers

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

Directory

• • Constant operators and pointers
    • Constant
      • Defined
      • Iota
    • Operator
    • Pointer

Summary

Define constants, constant groups, upstream expressions, iota,++/–, pointers

constants, operators and pointers

Constant

Defined

• Constants const are defined using keywords
• The value of the constant is determined at compile time, so the runtime cannot change
• A function in a constant expression must be a built-in function (because the return value of a function you write is determined at run time)

Example

const (    "text"len(text))

Use the value of the upstream expression in a constant group if you do not specify a default value

const (    a = 1   //常量必须有值，所以a必须指定值    b    c)fmt.Println(a, b, c)    //1 1 1

Iota

• Iota is a counter in a constant group, starting with 0, the value of iota is automatically incremented by 1 for each constant defined in a constant group.
• Each time a new constant group is defined, the iota will be zeroed

const (    "D"    e    iota    g)const (    iota//D D 2 3fmt.Println(k)          //0

Operator

++,--Only as a statement, that is, a single line of++

a := 1a++fmt.Println(a)var//error

Pointer

• Using the "." Direct manipulation pointer
• Use the "&" to take a variable address
• Use "*" to access objects indirectly through pointers
• Pointer default value is nil NOT NULL
• Type cannot be omitted when defining pointers

a := 1var pa *int = &afmt.Println(pa)  //0xc0820062e0//1var pb *int//nil