When the last parameter of the function is * ... T* (the three points in front of *t* are intentional), called the variable parameter function *: ' gopackage mainimport ' FMT ' func sum (Numbers ... float64) (res float64) {For _, Number: = Range numbers {res + = number} Return}func main () {FMT. PRINTLN (SUM (1.1, 2.2, 3.3)} "variable parameter function allows the passing of any number of (variable) arguments, within the function through a [slice] (https://golang.org/ref/spec#Slice_types) To access the values of these parameters (for example, parameter members in the code above). > only before the last formal parameter plus ... (three points) to indicate that this is a variable parameter function. # # Arguments vs. parameters in most cases the two terms can be common to each other, but the arguments generally refer to the arguments passed in when the function/method is called, which is a parameter, especially when the function is defined. ' Gopackage mainimport ' FMT ' func sum (A, b float64) (res float64) {return a + B}func main () {FMT. PRINTLN (SUM (1.1, 1.2)} ""-A and B are formal parameters-res is the return parameter of the specified name-1.1 and 1.2 is the argument # # ... Convert to slice inside the variable parameter function, ... The type T is actually a []t: ' Gopackage mainimport ' FMT ' func f (Names ... string) {fmt. Printf ("value:% #v \ n", names) fmt. Printf ("Length:%d\n", Len (names)) Fmt. Printf ("Capacity:%d\n", cap (names)) Fmt. Printf ("Type:%t\n", names)}func main () {f ("one", "both", "three")} ' ' Compile Run code output: ' ' > Go install github.com/mlowicki/ Lab &&./bin/labvalue: []string{"One", "one", "one"), "three"}type: the consistency variable parameter function of []stringlength:3capacity:3 ' # # type is not equivalent to the last parameter being passed into the slice function: ' ' Gof: = func (... int) {}f = func ([] int) {} ' the code above will error at compile time: ' ' Src/github.com/mlowicki/lab/lab.go:17:cannot use func literal (type func ([]int)) as type Func (... int) in assignment ' # # put three points on the other side the code snippet below cannot be successfully compiled: ' ' gopackage mainimport ' FMT ' func f (Numbers ... int) {FMT. PRINTLN (Numbers)}func main () {numbers: = []int{1, 2, 3} f (Numbers)} "" ' > Go install github.com/mlowicki/lab &&am p;./bin/lab# Github.com/mlowicki/labsrc/github.com/mlowicki/lab/lab.go:11:cannot use Numbers (Type []int) as type int i n argument to F ' "This is because it is necessary to pass a single argument to an int type, so it is clear that passing a slice type is not allowed. There is a trick in Golang to solve this problem quickly: "Gopackage mainimport" FMT "func f (Numbers ... int) {FMT. PRINTLN (Numbers)}func main () {numbers: = []int{1, 2, 3} f (Numbers ...)} "' When calling function *f*, three dots (... is placed behind the argument's * *, which is an easy-to-ignore change, but it passes *numbers* as a formal parameter list. This approach implements the use of slice as a parameter to invoke the variable parameter function. A variadic function is actually a syntactic sugar, which simply takes slice as the last parameter. The variable parameter function provides a richer representation of the APIs, while also allowing developers to no longer create temporary slicE.
via:https://medium.com/golangspec/variadic-functions-in-go-13c33182b851
Author: Michałłowicki Translator: NICEDEVCN proofreading: polaris1119
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