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.
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)) }
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 }
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) }
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 }
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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