golang variable parameters

Golang is a programming language that has been much discussed in recent years. Its simplicity, efficiency, and support for concurrent programming have made it the choice of many developers. In Golang, variable parameter function is a very important programming model. This article will explain Golang variable parameter function in detail.

1. The definition of variable parameter function in Golang

In Golang, variable parameter function is also called variable parameter function, which allows the function to accept any number of parameters. Golang's variable parameter function is defined by adding an ellipsis "..." in front of the parameter type. For example:

func funcName(args ...type) return_type {}

In the above function definition, the args parameter is an indefinite parameter and can receive any number of type type parameters.

2. The use of variable parameter functions in Golang

In Golang, the use of variable parameter functions is very flexible. It can be used to handle functions that need to receive any number of parameters, and can also be used to extend the functionality of other functions.

1. Use indefinite parameter function to receive multiple parameters

A common usage scenario is that when you are not sure how many parameters need to be received when defining the function, you can use indefinite parameters. function to handle. For example, the following function sum can accept any number of int type parameters and return their sum.

func sum(args ...int) int {

var total int
for _, v := range args {
    total += v
}
return total

}

When using the sum function, you can pass in any number of int type parameters:

sum(1, 2, 3) // Return: 6
sum(1, 2, 3, 4, 5) // Return: 15

2. Expand other functions Function

Another common usage scenario is to extend the functionality of the original function while retaining its functionality. For example, the following function print can extend the printing function of any function so that it prints out the function name and the total number of parameters before printing the function parameters.

func print(fn func(...interface{}) (int, error)) func(...interface{}) (int, error) {

return func(args ...interface{}) (int, error) {
    name := runtime.FuncForPC(reflect.ValueOf(fn).Pointer()).Name() // 获取函数名称
    fmt.Printf("Function %s got %d args: ", name, len(args)) // 打印函数名和参数个数
    return fn(args...)
}

}

When using the print function, you only need to pass the function that needs to be expanded as a parameter:

func hello(name string, age int) {

fmt.Printf("Hello, my name is %s and I'm %d years old.", name, age)

}

print(hello)("John", 25)
// Output: Function main.hello got 2 args: Hello, my name is John and I'm 25 years old.

Above In the example, the print function receives a variadic function as a parameter and returns a new variadic function to extend the functionality of the original function.

3. Precautions for indefinite parameter functions in Golang

When using Golang indefinite parameter functions, you need to pay attention to the following issues:

1. In indefinite parameter functions There can only be one variable parameter

Golang does not support function definitions with multiple variable parameters. For example, the following function will cause a compilation error:

func test(a ... int, b ...string) {}

2. The variable parameter must be the last parameter in the function parameter list

When the function is defined, the variable parameter must be The last parameter in the parameter list, for example, the following function definition is invalid:

func test(a ...int, b string) {}

3. Variable function receives parameters When, the slice type cannot be used

Inside the variable parameter function, the parameters cannot be directly converted to the slice type. If you need to use slices, you can do so by passing parameters to other functions:

func sliceFunc(args ...int) {

slice := make([]int, 0)
for _, v := range args {
    slice = append(slice, v)
}
// 使用slice

}

The above are Golang variable parameters Detailed explanation of functions. Through variable-argument functions, we can handle an uncertain number of function parameters more flexibly and achieve more efficient and elegant code.

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