Detailed explanation of golang learning 'indefinite parameters'

Golang is a powerful programming language. Its grammatical structure is simpler and more direct than other languages. It is especially suitable for processing large amounts of data and solving high concurrency problems. One of the advanced features is variable arguments, also known as variadic arguments, which allow a function to accept an indeterminate number of arguments, thereby increasing program flexibility and reusability.

1. Use of variable parameters

In Golang, we can use ellipses (...) to indicate variable parameters, which means that a function can accept any number of parameters. . Here is an example:

func sum(nums ...int) int {
    total := 0
    for _, num := range nums {
        total += num
    }
    return total
}

func main() {
    fmt.Println(sum(1, 2, 3, 4))
    fmt.Println(sum(5, 6))
}

In the above example, the function "sum" defines the variable parameter "num" using an ellipsis (...), which indicates that any number of integer parameters can be accepted. We can see that in the "main" function we can pass an indeterminate number of arguments to the "sum" function which will be used to calculate their sum.

2. Type of indefinite parameters

In Golang, the type of indefinite parameters can be any type, including custom types. The following is an example of a custom type using indefinite parameters:

type Person struct {
    name string
    age  int
}

func averageAge(people ...Person) float64 {
    total := 0
    for _, person := range people {
        total += person.age
    }
    return float64(total) / float64(len(people))
}

func main() {
    p1 := Person{name: "Tom", age: 20}
    p2 := Person{name: "Mary", age: 25}
    p3 := Person{name: "John", age: 30}

    fmt.Println(averageAge(p1, p2, p3))
}

In the above example, we define a custom type "Person" to represent person information. We also define a function "averageAge" that can accept an indefinite number of "Person" type parameters and calculate their average age by iterating over these parameters. Finally, in the "main" function, we can pass any number of "Person" type parameters to the "averageAge" function.

3. When to use indefinite parameters?

Using variable parameters can make the code more flexible and reusable. It is very suitable for the following situations:

1. Build a function that accepts any number of parameters;
2. Changing the number of parameters of a function does not affect the stability of the program;
3. Build a dynamic type container function that can save any type of data.

4. Limitations of indefinite parameters

Although using indefinite parameters can improve the flexibility of the code, you need to pay attention to some details when using indefinite parameters.

1. Indefinite parameters can only be at the end of the parameter list of the function;
2. Indefinite parameters cannot be used in interface types;
3. Indefinite parameters need to pass at least one parameter;
4. Indefinite parameters are treated as a slice type inside the function, which means that all functions that use slices also apply to indefinite parameters.

5. Summary

In Golang, using indefinite parameters can make the code more flexible and reusable. It's great for building functions that accept any number of arguments, or building a dynamically typed container function. When using variable parameters, you need to pay attention to some details. For example, variable parameters can only be at the end of the parameter list of the function, and at least one parameter must be passed for variable parameters. When writing code, rational use of variable parameters can make the program more elegant and concise, and also help improve the maintainability and readability of the code.

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