Example Analysis of variable declaration and assignment in go language
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Variable
A variable is an abstract description of a space in memory. The type of variable defines the size of the space and how it is parsed.
Variable type 1 in Go
Bool byte complex64 complex128 error float32 float64 int int8 int16 int32 int64 rune string uint uint8 uint16 uint32 uint64 uintptr
Declaration and assignment of variables 11
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Package main
Import "fmt"
Func main () {
Var x string
X = "Hello World"
Fmt.Println (x)
}
Mode 2
Note that x: = "Hello World" is equivalent to var x = "Hello World"
Automatically infers the type and must be inside the function body
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Package main
Import "fmt"
Func main () {
X: = 1
Fmt.Println (x)
}
Multiple assignments 1
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Var i int
Var U, V, W float64
Var k = 0
Var x, y float32 =-1,-2
Var (
I int
U, v, s = 2.0,3.0, "bar"
)
Example:
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Package main
Import "fmt"
Func main () {
Var a string= "jonson", "jackson"
C true,false d: =
Erecent fjorg: = "jonson", true,123
Fmt.Println ("a:", a)
Fmt.Println ("b:", b)
Fmt.Println ("c:", c)
Fmt.Println ("d:", d)
Fmt.Println ("e:", e)
Fmt.Println ("f:", f)
Fmt.Println ("g:", g)
}
Zero value problem
If the variable initialization does not assign a value, the default is empty.
Example:
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Package main
Import "fmt"
Func main () {
Var an int
Var b string
Var c float64
Var d bool
Fmt.Printf ("% v\ n", a)
Fmt.Printf ("% v\ n", b)
Fmt.Printf ("% v\ n", c)
Fmt.Printf ("% v\ n", d)
Fmt.Println ()
}
Constant
Once a constant is declared, it cannot be changed, and the constant must be assigned an initial value. This code is invalid func main () {const x int}
Valid:
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Package main
Const (
M = 1
N = 2
)
Func main () {
Const k = 8
}
Iota usage
Iota loops from 0
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Const (
A = iota
B = iota
C = iota
D = iota
)
Equivalent to:
Const (
A = iota
B
C
D
)
Use case:
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Package main
Import "fmt"
Func main () {
Const (
A = iota / / 0
B / / 1
C / / 2
D = "ha" / / Independent value, iota + = 1
E / / "ha" iota + = 1
F = 100 / / iota + = 1
G / / 100 iota + = 1
H = iota / / 7, restore count
I / / 8
)
Fmt.Println (a recalcitrance brecrium crecinct d recorder e recorder f g jiggy pr I)
}
Abnormal iota1
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Package main
Import "fmt"
Const (
I, 1
