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What are indefinite parameters in go language?

Jan 17, 2023 pm 03:33 PM
golang go language

Indefinite parameters means that the number of parameters passed in by the function is an indefinite number; the indefinite parameter declaration uses the syntax format of "param...type". Characteristics of indefinite parameters: 1. All indefinite parameter types must be the same; 2. The indefinite parameter must be the last parameter of the function; 3. The indefinite parameter is equivalent to a slice in the function body, and the operation of the slice is also suitable for the indefinite parameter operation; 4. Slices can be passed as parameters to indefinite parameters, and "..." must be added after the slice name; 5. The types of functions whose formal parameters are indefinite parameters are different from those of functions whose formal parameters are slices.

What are indefinite parameters in go language?

The operating environment of this tutorial: Windows 7 system, GO version 1.18, Dell G3 computer.

What are indefinite parameters

Indefinite parameters mean that the number of parameters passed in by the function is an indefinite number.

package main

import (
    "fmt"
)

/*
不定参数函数
*/
func Add(a int, args ...int) (result int) {
    result += a
    for _, arg := range args {
        result += arg
    }
    return
}

func main() {
    fmt.Println(Add(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
}
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The Go function supports an indefinite number of formal parameters. The indefinite parameter declaration uses the syntax format of param...type

The indefinite parameters have the following characteristics:

  • ①All variable parameter types must be the same.

  • ②The indefinite parameter must be the last parameter of the function.

  • ③The indefinite parameter is equivalent to a slice in the function body, and the operation of the slice is also suitable for the operation of the indefinite parameter.

  • ④ Slices can also be passed as parameters to indefinite parameters, and "..." must be added after the slice name.

package main

import "fmt"

func Add(arr ...int) int {
	var count int
	arr1 := arr[1:]
	for _, val := range arr1 {
		count += val
	}
	return count
}

func main() {
	slice := []int{1, 2, 3, 4, 5}
	//array := [...]int{1, 2, 3, 4}
	fmt.Println(Add(slice...))
	//fmt.Println(Add(array...))  //cannot use array (variable of type [4]int) as parameter of type []int
}
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  • ⑤The types of functions whose formal parameters are indefinite parameters are different from those of functions whose formal parameters are slices.

package main

import "fmt"

func Add1(arr ...int) int {
	return arr[0]
}

func Add2(arr []int) int {
	return arr[0]
}

func main() {
	fmt.Printf("%T\n", Add1)
	fmt.Printf("%T\n", Add2)
}
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What are indefinite parameters in go language?

Passing of indefinite parameters

func SetData(args ...int) (result int) {
    //不定参数的传递
    return Add(1, args...)
}
func main() {
    fmt.Println(SetData(1, 2, 3))//输出7
    array := []int{1, 2, 3, 4}
    fmt.Println(Add(1, array...))//输出11
}
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Any type of indefinite parameters

/*
任意类型的不定参数,用interface{}表示
*/

func MyPrintf(args ...interface{}) {
    for _, arg := range args { //迭代不定参数
        switch arg.(type) {
        case int:
            fmt.Println(arg, "is int")
        case string:
            fmt.Println(arg, "is string")
        case float64:
            fmt.Println(arg, "is float64")
        case bool:
            fmt.Println(arg, " is bool")
        default:
            fmt.Println("未知的类型")
        }
    }
}

func main() {
    /*输出结果:
                12 is int
                haha is string
                12.5 is float64
                false  is bool
                -12.5 is float64
    */
    MyPrintf(12, "haha", 12.5, false, -12.5)
}
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[Related recommendations: Go video tutorial, Programming teaching

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